I used teeth whitening in the past on two separate occasions using two different methods and two different dentists. Since both scenarios took my insurance, I don't recall the price that I paid.
Be careful, though, or you may encounter the same problems that I had:
Experience #1 - teeth whitening at the dentist's office. Dentist applied a series of chemicals to my teeth and then applied a blue light to "set" the chemicals that actually whiten the teeth. My teeth must be particularly sensitive, because I suffered horrific pain. The best analogy I can come up with is this: if you took a hot steaming cup of coffee and inserted a couple of ice cubes in it, and the crackling that you get in the ice cubes - the nerves in my teeth reacted in much the same way. My head felt like it was going to explode. I couldn't tolerate the pain, so I never went back for the multiple sessions.
Experience #2 - teeth trays were made by the dentist and gels were provided to me to fill each night and wear while sleeping. The trays fit really well, but the gel stuff made the nerves in my teeth ache in agony. I tried different strength of gels with different chemical compositions, but they all caused my nerves to react the same. I tried for probably a week using the trays, and I had to take two Tylenol PM's when I went to sleep to try to minimize the pain. I'd still wake up each night wishing that I had a chainsaw to lop off my head. The trays/gel was too painful for me to to continue.
So, to sum things up, I paid a lot of money - and insurance paid a CRAPLOAD of money - for something that I couldn't use because of the pain.
Most people have lots of success with both of these methods of teeth whitening, though.
I ended up with vaneers, which is a different story altogether.