I wait for "black Friday" sales at Performance Bike. Don't have a local store so will order them online unless I'm in a town that has a store on Black Friday.

Anyway, sometimes they are on sale other times of the year. I run 700x25 tires so a little different, but usually get them for around $2.25 each. Will usually buy 10-20 tubes at a time so will have plenty for our local bike group.