I personally don't do it. But I also don't drink or eat too much candy. I simply like being the healthiest person I can be.
But, I have friends that do it. It's certainly not as bad for you as cigarettes or chewing tobacco, but, it still is tobacco. Honestly, if your not competing for the Olympic trials or big races/meets that win you something big, then it won't be a big deal. If your like me, and just want to be the best you can be (meaning every second in a race counts), then it may make a small difference.
As for price, if you go to hookah bars, it's like $10+ per visit. If you buy your own Hookah, it can run anywhere from $30-$100+ depending on what size you buy. As for the tobacco, it's relatively cheap if you buy it in bulk.