Where can you buy cheap acrylic? I am looking at 1.5" about 120"x48" but all the sheets are like $4,000! I saw at thread on here and his window was same thickness and about same size and he said he bought his for $500?!?
Do you have a Laird's near you?
Call all of the plastic warehouses or sign making warehouses near you.
Watch your local classifieds also. Lookup plexi, plexiglass, acrylic, plastic sheet, bullet proof, bullet resistant, etc. People are selling leftovers or remnants all the time.
Good luck.