Suppliers for Tail light Lens Material

Anyone know of a technical name for the plastic used on taillights? Any places to buy it from? Preferably a supplier and not a custom shop. Either something like this link or prismatic material. (I know hitec and custom classic have prismatic but it's way overpriced I'd rather buy large quantities)

http://www.billetspecialties.com/assets/500/0000000327-prod.jpg