I like the design visually but I think the navigation is confusion
You seem to have a sort of "studio" menu on the top
The on the left you have a "type" menu below which you then have a "hot picks" which seems to be the main way you want people to navigate the site (as it has the huge popout menus)
Id drop the "studios" from the menu bar as I think thats a minor way for people to search, and Id give the user 2 ways into the products
select type > then select show (or all)
select show > then select type (or all)
If you do this through sub pages (i.e. have a page for "Orginal Art", a page for "Superman" etc which list the subcategories) I think it will be easier to understand and also it'll help you for
SEO too (assuming you optimise those pages for those terms - which I can see you havent done yet as your title tags and titles are generic on each page from what I can see)
Mod Rewrite on the urls wouldnt hurt either