I agree with Marie, this is a project that is usually more trouble than its worth -- HOWEVER - there is no feeling like making a complete cage all by yourself and then watching all the fellas enjoy their time in it. It is really a rewarding experience like no other.
I took bits and pieces of old cages and did some fancy fastening etc. However where it was critical, I also purchases some wire mesh (
http://www.bwire.com/index.html ) for a few sides and the bottom of the large indoor cage.
Took me a while, on and off working for about 8-10 months, but like I said now that it is done, I don't care what it cost me in time or money, it was worth it!