You probably want 2 mil 2" x 8" bags, here are a few vendors, I haven't used any of these personally, but it all comes out to just shy of $20 for 1000 bags delivered with any of these suppliers (some include "free" shipping):
http://www.royalbag.com/2_x_8_2_mil_...sable_bags.asp
http://www.fetpak.com/whstore/main.pl/itl?15
http://www.papermart.com/Product%20P...pID=19058#4367