Crest white strips?

So im looking for a at home whitener for my teeth, Im not willing to go over $60. I would get my teeth professionally done however I heard it kinda ruins your enamel and sensitivity of the teeth. So im choosing another route. I also wear a retainers from braces (in 16) they look like invisaline so its like dentures lol I only wear them at night. any good information or tips on any solution or if you think I can get them done professionally I would absolutely love it!!!!