Crest Whitestrips not only works well, but it's easy to use. You can get the CONSUMER version around ~$40 at Target, Walmart, or your local grocery stores. If you would like, my class is doing a fundraiser selling the PROFESSIONAL version of the Crest WHITESTRIPS for $35.00.
CONSUMER version is less potent (less peroxide concentration) and it's only a 2 week supply
PROFESSIONAL version is more potent (more peroxide concentration, whites teeth faster) and a 3 week supply
If you're or anyone else is interested please let me know.
Go with Crest Whitestrips...I'm using them and they work great for a cheaper price.