Cost isn't that primary issue for me - I just feel that it's a tragic waste sometimes when you do a flat-happy ride and get 2, even 3 flats in one ride. If you use hi-quality Bontrager inner tubes like I do (they are MUCH better than the cheapos - you can feel the difference just holding them in your hands) , that's a $24 bike ride, and it seems like a huge waste to discard a nearly brand-new tube when you can just fix it.