I had the laser whitening done at my dentist for $550. It has been 13 months since I had mine and it still looks great. My dentist said that people tend to get it done every year. The only problem I had with it was the pain. My teeth are super sensitive and when it came to the last application of gel and the laser it was very painful. I got shooting pains in my teeth and up into the gums for about 4 days after and had to be a bit careful with hot and cold stuff, but they are fine now.
I highly recommend it and have tried some of the home whitening kits, but never got a result as good.