To add to what CRM you can also go to lowes and ask to see there scrape acrylic. They also sell it much cheaper.
trreherd thats what I did when I did the panels in my sump. Like CRM said a simple 12x14" square can close to $10, and thats not even for 1/4" sheets.when you say expensive how much are we taliken per square foot?
I will look into geting it scrap.