Is it better to get your teeth whitened or use whitening strips?

And what are the best whitening strips that are still cheap.
--------------------
I got my braces off awhile ago and really wanted to whiten my teeth and i have been using the crest 3D whitestrips. and they work REEEALLLLY well:D. i think they were $30. but still way cheaper then getting them professionally whitened. btw it comes with 20 strips in the pack ...hope this helped:)
Source