[Nyx]

I never heard of it before I looked it up just now, but it looks like it's really expensive and the reviews I saw said it's really painful and not worth it. I had Crest Whitestrips and they worked pretty well (I bought them because they were on clearance and wasn't expecting much). I only used them for a few days and it whitened my teeth a few shades.

Have you tried whitening strips you buy at the store, yet? They might take a little more time, but they're the cheapest and most painless way, I think.