I have one of these. They are ordered from ebay. They aren't the best choice for ferrets though. Mine is empty right now. I now have a superset defined habitat for ferrets. I thought they'd hate it but they love it.
Ratties: Jinx, Gus-Gus and Cookie
Piggies: Cupcake, Care Bear, cleo, snickers and rayne
Ferret: Spaz, Bruno, Bruce, Panda, Princess, Kilo and Baby
Dog: Winnie, my golden retrieved/basset rescue from TCAR.