PVC
Polyvinyl Chloride
PVC is a colorless, rigid plastic with a glass transition temperature of 80C. Extrusion of PVC may be difficult/dangerous because it degrades at high temperatures, producing carcinogenic material. However, this may be reduced with plasticizers that lower the glass transition temperature.
Suppliers
Check the forums... someone might be able to ship you some for cheap.
otherwise see Printing Material Suppliers