Check out the pics of alternative cages in the galleries....... if your dad is a "handy man" like mine is
he might have those items laying around in the garage. My daddy always had those shelving pieces some people use laying around.
Definatly check yard sales and thrift shops too. I've seen grids at those places for a steal. You could also check Craiglslist.
You can also ask stores if they have any advertising signs they don't use anymore. They usually make them from coroplast. They likely would give them to you for free. If you got enough pieces, you could clean them up, and tape them together!
Also, just call the regular sign stores... sometimes they will give away what they consider to be "unusable scraps". That's how I got mine... they gave me three pieces about 16 inches wide by 4 feet long that were destined for the trash.
But I do feel your pain... whenever my mother comes to visit me, she scolds me about my cage. She also thinks its too big and extravagant.