poly carbonate is a stronger material than acrylic. It is less brittle and easier to drill and cut. It is more expensive and scratch prone. Abrasion resistant poly carbonate is approximately 1.5-3 times more expensive than regular poly carbonate. I get mine from a local plastics company and surplus store. Look up in your phone book "plastics" in the yellow pages. Call a plastics company and ask them if they have any scrap abrasion-resistant poly carbonate. That is the cheapest way to get it. I would use nothing less than 1/4in polycarbonate due to its inherent flexibility.3/8 in is strong and 1/2 in is very strong.
www.McMastercarr.com sells both poly carbonate and acrylic and so does
www.usplastic.com