I am in the process of doing that right now and am so pleased with the results!
I tried the Crest strips first but couldn't use them. They are VERY strong (peroxide I think) and after three days my gums were bleeding like crazy!
Then I read in the paper that dentists in town were offering teeth whitening at the reduced price of $175 with the proceeds going to an interfaith dental clinic (for low income people without dental insurance).
As luck would have it, my dentist was participating and I had an appointment scheduled the next week. So I asked her about it, and she said all the kits the clinic gave them were gone, but that she would do it for me with one of her kits for the same price!
BTW, prices have really come down since this first started - she originally charged $600-$800 but her regular price now is about $225-$250.
Anyway, she also gave me a kit that is for sensitive teeth. I am 4 days into it and can already tell a huge difference - and I don't have any problem with my gums bleeding!
So..you might want to check with your dentist to see if the prices have come down. If you have any sensitivy in your teeth, it would be worth working with a dentist.