This has been discussed quite a bit -- but that's not to bash you for doing so again, more to say that based on my reading of those threads, I'd be comfortable re-using tubes once or even a few times. In my 22 years with this plane I've always changed tubes with tires, but after reading of others' experiences here it sure seems to be rare for tubes to go. In fact my current "air stop" tube on the right side tends to slooowly leak down so the next time I change tires I'll be swapping back in the previous tube, which held the air just fine.
The key is to use plenty of talc and otherwise properly install so there aren't creases etc.