Don't know if I can put a link on here, and forgive me if I am not supposed to, but freecycle.org helped me with my cage. I put a wanted ad on there for storage cubes/grids and was given 12 panels by a lady that did not need them for her scrapbooking supplies anymore. She did not give the connectors, but I had zip-ties. Was offered some coroplast, but it was not large enough, so I purchased the $17.00 sheet of coroplast from a local sign shop and built my cage. One hour and $17.00 and I have a totally functional cage (not saying all my lines are straight, but it works).
freecycle.org really helps keep things out of landfills, and they have a ton of different chapters. It never hurts to ask, and offer the things you would normally trash. From cardboard to salt shakers, someone somewhere can use it... so why throw it away.
Maybe this will help you to keep your costs down too.