Throw away a perfectly good tube?!? I've been known to pick up other people's tubes, patch them, and then get a free tube! 1.50$ for a patch kit will yield me 6 'new' tubes. Try to beat that price with your 'sales'. I've got a few tubes running with more than 5 patches, that have been in the bike for about 8 years without trouble.
I only throw a tube away if it has an unpatchable hole, like a tear. Sometimes seam holes can be touchy to patch, too.
peace,
sam