For me, the cost is worth it. I end up paying ~$50 per tyre, which is about 2X what you can get cheap tires for, and I get more than 2X the life out of a set of tyres. That however is not what makes it worthwhile for me - the bike is my main mode of transportation, and the PITA factor of having to fix a flat in the morning, when I am trying to get to work has a lot of negative value to me. I ride about 3,000 miles per year, and end up replacing one tyre about every 2 years, which means that I am paying about $0.10 per day for my expensive tyres. If I got no more life from the SMP tyres than from a cheap tyre, but was assured fewer flats, the added expense would make it worthwhile for me, the fact that on a cost per mile basis, the SMP costs no more makes it an easy choice.