He allows custom orders, with any combination for actuators customers need, so its not so easy to possibly list all prices for combinations. They are factory after all and can build anything.
There is an effort to standardize some of these actuators or kits to be able to list a price for them with shopping cart etc, but it would be on another website for that. The current website is more like show room to show some of the products...
That's understandable and it's great that Shao can tailor orders for each and every need. Maybe in the future he might consider an upfront price on the site for the most common kits such as the 4dof.
I won't even try to guess how much the kit in your picture would cost