I'm also a big fan of Martins cages, they may not look as pretty as some of the other cages out there but the truth is your ferret won't notice! These cages aren't designed for you they are actually designed for the critters that use them. They are VERY sturdy and built to last. They are practiacally chew proof as well. The cheapest place to get them is from here
The Ferret Store because they don't charge for shipping. But you can also get them directly from their website Martins Cages