I wouldnt use formica either. Same reasons.
If you don't want to have to deal with cutting a big piece of plexiglass for them, Home Depot has smaller pieces (11x14) for $2.50 each. You could get a square up to 11" out of it. The cutting tool is less than $4. You could just buy one piece as you need them. A 30x36 is around $15.