Sort of not in the theme here. But what brands should I look for when buying models?
It depends on the scale, and heavily depends on what cars you're into.
There is a trend nowadays, a lot of new 1/18 manufacturers are making sealed 1/18s with non-openable parts, and some of older manufacturers moved to sealed models too. For some people this is fine, but first - the prices aren't lower than for those with opening parts, and they usually consist of so few elements, even the wheels are just glued to solid metal struts, like toy cars. But if you don't mind sealed models, and sometimes it's the only choice, look for Spark and TrueScale Miniatures (Also TSM makes openable from time to time too) - they have really amazing detail, which somewhat compensates the fact the models are sealed.
As for brands:
AutoArt is the most common answer, they always make very accurate models with flawless panel gaps and paint all around, the opening bits are traditional and nothing special, but good package all around. Especially older ones - some new AutoArts are from composite materials and quality became a little worse. But sometimes AutoArt has been overlooking the car proportions: one of worst examples of that is 1973 Porsche Carrera RS. If you're in search for old Carrera, best to find very old Minichamps dealer edition model, the one with openable bits. But it's real rare now. Or get some Schuco. And also nowadays AA makes some sealed models, or semi/sealed, so beware.
Kyosho is one of other common brands, but honestly I try my best to avoid that. First of all, most of their engine and interiors look like average-built plastic models at best, with cheap metallic paint. Also they have some QC issues, some parts are badly glued or falling off, and some materials are aging really bad - I had a Lancia Stratos from Kyosho, and some parts on metal body were plastic, like rear spoiler, or maybe whole rear body panel, and it started having some yellow cracks. Needless to say, I store them in glass shelves, away from direct sunlight and in a smoke-free apartment. While the described issue might be only the case with one particular model, I'm still finding them not too good enough in general for their price.
Schuco is real nice brand, focusing around Porsche and VW, it's a first source of models if you're into Porsche imo. Quality is great, and you have a lot of interesting opening bits, like fuel tank hinges.
Minichamps is now making sealed metal models, with level of detail being worse than Spark or TSM, but before they were making from OK to real nice diecasts with opening bits. Like that old Carrera I mentioned above. They have also made group 5 Capris, which are probably little too priced for the detail, but nevertheless, are looking epic.
Norev is an okay lower-price manufacturer, they aren't shooting the stars, but also the prices are nice and low. And some models are really well, like 80s Merc SL.
Solido is another entry-level manufacturer, for the most cases you don't need to look at them, but sometimes they release cars that are very good with proportions. Like their 427 Cobra or Mini, which are miles better in proportions than Kyosho one.
SunStar is another entry-level manufacturer, and a mixed bag - some of their models are quite okay - like Lancia Stratos (which, compared to Kyosho's above, has less detail and a little rougher mold, but the proportions are close, and it will give you much less trouble, and much cheaper. Also the engine and interior are looking almost identical in quality and detail), or MK2 Escort, but on the other hand they have a lot of cars really toy-like, with very bad proportions. They also have
SunStar Platinum series, producing '60s American cars, with
a lot of interesting moving bits, from gloveboxes, to window wipers but they save money on materials big time, and you will inevitably break some parts. And they have some various paint problems, starting with the body paint, finishing with the weird sticky paint on tire whitewalls, and interior bits. But they are looking real nice. In the end of the post I'll attach a photo of SunStar Platinumc model.
If you're into American cars, you will encounter some other manufacturers:
Ertl/Autoworld: a quite old manufacturer, producing muscle cars. Had some problems with paint and quality is a mixed bag, but recently they are re-issuing a lot of older models, with much better paint quality and detail. And they're quite cheap. I'm quite positive about them recently.
Also ERTL Authentic series molds are very nice, like 1971 Charger. The quality of ERTL, and honestly as well as every other Americana-related models described below, can vary from model to model - for example 1971 chargers have folding lights, openable glovebox, very detailed engine, working transmission, drive shaft and differential (!), while ERTL's 77 Trans Am is a very basic model all around.
Highway 61 and
GMP not sure if it was the same manufacturer, but HWY61 models were always very nice (Barracuda I posted before), and GMP was quite mixed bag, but still very cool, producing both street and race cars. But being old models they are becoming real expensive. They both were acquired by Greenlight recently, and recently re-issuing a lot of models, which are very nice too.
ACME I'm not sure what it is, probably some marketing branch that uses GMP/HWY61/Lane molds to make some exclusive model versions, real nice too.
Lane Exact Detail was producing some muscle and race cars, quality about the same as GMP.
Greenlight is a more mainstream brand, which had some nice and not expensive unique models, but always saving money on paint and materials. Since they've acquired GMP/HWY61 their mainstream branch became real low quality - i'd say avoid it. The last good model they produced under their mainstream branch was 1978-81 Camaro. They are also producing some Indycar diecasts, but the level of quality and detail there is also very basic.
Carousel 1 was the brand that made very nice old Indycars, and also some Porsche and Corvette race cars from 70s. The level of detail of Indys was real great, Corvettes - not so great, amazing at some places, but sub-par in the engine and interiors. Still love those models.
Later on that brand became
Replicarz, now they release some diecast and resin, openable and sealed models, but in a very small quanity, so the price is high.
If you're into Nascar, look for
Action models. They produce 1/24, 1/18 and 1/16, also ERTL was making some older Nascars, but Action has more details, indlucing openable flaps. But the difference of level of detail between their 1/24 and 1/18 is really small, but once you have luck to get their 1/16 model - oh my oh my! They are amazing. The level of detail like doubles or triples from their 1/18.
If you're into Australian models, you basically have 2 choices -
Biante and
Classic Carlectables (which is probably a branch of Biante anyway?) Both are very nice, on a level with Autoart, and Classic Carlectables even exceeds the level of AutoArt. They both produce street and race cars, old and new. But Biante has some QC issues on their recent models. Got myself Classic Carlectables Kevin Bartlett's Camaro from Bathurst race, and it's epic.
Now, I've left the most tasty stuff for the last bit.
Exoto has produced a lot of old race cars of various disciplines and eras, and they are amazing for the most part. They have a ton of openable bits, from traditional doors, to some various hinges, and sometimes you can tear the whole model apart, like their Chaparrals, and find amazing level of detail underneath - like the actually modelled back sides of switches on the dash panel, with wiring and contacts!
And sometimes on eBay you can find them for a decent price, comparable with new sealed resin models (this is crazy, I know).
They had some quality issues with paint and decals, especially on Can-Am porsche, but if you keep them away from moisture/sunlight and smoke they should be fine. I've got some Exoto 260 and 289 cobras, Chaparral, Ford GT40, few Grand Sport Corvettes (actually, corvettes are one of the lower quality/detail models of them, especially the non-grand sport were build in partnership with Revell, but they are still great).
CMC is another brand that makes epic all-openable models. You got various hinges openable, leather belts with realistic locks holding the hood/trunk, wheels that you can un-bolt with special lug nut key, etc etc, Prices are high, but they truly deserve that.
GMP Masterpiece series was a branch of GMP, focusing on few american cars (C2 corvettes, 1970 GTX/Roadrunner, Ford Fairline), as well as some race Ferraris. The ferraris you can tear the body panels apart, take the wheels off using lug nut key, also they have a lot of openable and removable bits, as well as working gearbox levers. Corvettes and Roadrunners/Fairlanes have evrything that can be openable working, including fuel tank hinges, glove boxes, few various bits, AND you can roll windows up/down using handles in the doors. Corvettes are known for paint rash problems, though. Roadrunners are now re-issued by Greenlight. I haven't seen any of re-issued ones in person, I would be intersted if quality got better or worse.
Almost Real is new kid on the block from China, they started with old Land Rovers with the level of detail comparable to CMC standards, now they are also bringing some modern street and race cars, as far as I know.
As for where to buy: there are several stores, and of course you can look in some of your local stores to have a glance on the model in person, but basically I'd say eBay is your friend.
The prices though are very depending on the number of models issued, and how long they ended the production. For example, AutoArt's WRC Subaru now have similar price, like some masterpieces from exoto or CMC. Not that AutoArt's models are bad, but the level of craftsmanship involved is totally different, and the whole pricing is now generated by rarity.
Maybe I missed something, in that case I will edit my post later.
And here's the picture of SunStar Platinum Mercury Montclair.