Best teeth whitening for $25 or under?!

Question: Okay so I'm 13 years old and I drink alot of coffee so my teeth aren't very white. I also have enamelhypoplasia which means my enamel is thin and my teeth are sensitive. I need a good teeth whitening system that is $25 or under and won't hurt my teeth very badly. I don't mind abit of pain but I don't want it to be REALLY painful.
So, best teeth whitening system?

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Answers: Okay so I'm 13 years old and I drink alot of coffee so my teeth aren't very white. I also have enamelhypoplasia which means my enamel is thin and my teeth are sensitive. I need a good teeth whitening system that is $25 or under and won't hurt my teeth very badly. I don't mind abit of pain but I don't want it to be REALLY painful.
So, best teeth whitening system?

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Maximum Teeth Whitening is fast acting and side-effect free. I find it convenient to use. It only takes you to add another $4.97 since it costs $29.97. But I swear, it really worth it!

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Crest has whitening trays. Do not get the strips, they fall off your teeth and don't work as well.

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