I was very lucky in that department. The head of my department decided one day that all the framed artwork in our office was causing too much of a glare so he had me remove all the Plexiglas from them. He told me to throw out 21 2 x 3 foot panels, but thinking ahead, I asked if I could have them.
When I was designing my set, I tried to make sure all of the consoles were no more than 3 feet wide, so I'm set. If you guys were closer, I totally would donate any leftovers for your production. I wonder if any frame shops or anything in your are would have anything similar? You might also check thrift stores for old plexi poster frames -- I think you'll need something under your consoles or they're going to sag like crazy.
They don't really have to be long continuous pieces, either -- you can always tape together sections with clear packing tape since you're covering everything with the displays, anyway.
Just some ideas to stay on the cheap!