M.P.
I had this same issue. I found a hanging clothes organizer (hangs from the closet rod) @ Ikea that has shelves that fit most of his large toys (like his Little People garage, Imaginext sets). The bottom bin also has a small front on it so he can put things there that might otherwise roll out. It was only $6 and it works great for us! Maybe you could hang it from the ceiling if there isn't enough closet space. Here’s a link to it on Ikea’s website:
http://www.ikea.com/us/en/catalog/products/50188957