in Lansing, you can also check Padno's...they have a "usable scrap" yard, and always have lots of stuff there, alot of it is actually new steel bought for contract jobs and not used, etc...
Buy the good stuff from Alro for the main hoops in the cage, and see if Padno's has something you can use for the rest of the parts of the cage...could easily save alot of money that way, but the trade off is time...you have to walk around the yard/building and pick out what you want, and take it to the scale. Thier stock changes often, and they may or may not have something you could use on any given day.
They sell everything by the pound, but I dont know off the top of my head what the prices are. I do get alot of stainless there, but I often have another guy go get it for me.