The "good stuff" means many things to different people's needs.
If by this you mean excellent flexibility and scratch resistant, it's not cheap stuff.
And then there's the waste of material to make what you want (front or rear glass panel replacements)
Depending on what kind of model of body you're looking for, Fivestar makes a variety of polycarbonate versions that probably would save you time and be about the same cost. Depending on what kind of replacement for glass you're looking for, they will even custom make an oversized version for you to trim as required. They make more than Late Model versions;http://www.fivestarbodies.com/index.php?p=catalog&parent=79&pg=1
I'd give them a call too see if they can help you out and compare time, shipping, and running around costs depending on the type of finished result you want. For race cars, I've always purchased "factory" front versions. Side windows and rear, used to buy flat stock Lexan.
36728 89th Street
PO Box 700
Twin Lakes, WI 53181
8 am - 5 pm Central
If it's something custom you're looking for, there are a variety of types of clear plastic such as Lexan, Poly's, Acrylic's. You may want to try Piedmont Plastics. Really good materials, but.....Not cheap.http://www.piedmontplastics.com/prodtype.asp?ID=10
Dealers in Ontario:
GTA East (Head Office)
938 Tapscott Road
(416) 281-4300 1-800-268-6784
975 Bleams Road
(519) 725-6111 1-888-669-8922