Any plastic/sign supply shop should be able to get you a sheet of 1/2” cell cast fairly easily for $250 or less. Most of the time material cuts are free if the material is bought through them. Don’t pay more than $250. You will find a better deal if you search and call around. Most company’s will give you a quote within 2 minutes of being on the phone or within 24 hours through email. I get 1/2” sheets for $180 CDN.