Cheap tubes

should do a group order and save some dough

http://www.biketubes.net/

MEC is another option, at $3.75/tube and no shipping…

http://www.mec.ca/Products/product_detail.jsp?PRODUCT<>prd_id=845524442096351&FOLDER<>folder_id=2534374302693707

If you do a bulk order from them someone else has to get the tubes cross border as well.