I have never seen anything like the c&c cages before, really great idea! I think I like the stacked bin cages best though, they just seem a bit sturider somehow, but I suppoes it depends how you make it!
The cages with the folding door reminded me of something that I saw on ebay today, they were funny cages, a cross between the zoo plus wooden cages and a pet shop one with the sliding front panels.
I will see if I can find them for you . . .
Arena 60 Small Animal Cage with Wooden Runs on eBay (end time 12-Jun-10 13:57:35 BST)
here we are found it!!