My goodness, how many flats do you get???? 50 tubes would las me more than a lifetime. I haven't had a flat in years [I know...I shouldn't have said that!!!]- If you're getting a lot of flats, figure out why, and correct the problem.

Also, when you buy tubes, buy GOOD ones, like Michelins. Generic/low-quality tubes SUCK! I'll never forget the crappy Kenda tubes that came with my first road bike- I got a flat before I ever even rode the bike- the valve stem partially ripped out of the tube! And I had several flats and blowouts on that bike in the first few hundred miles of riding- until I changed the tubes and tires for quality ones.