White teeth

So, I'm realizing that I don't have the whitest teeth. I bought Crest white strips, but I put one on my top teeth and thought I might start to gag. Not a big fan of non food items in my mouth. I could try again, and just gag my way through it, but I thought some of you might have a few suggestions for me. I know I could just go to a dentist and have him do it. I'm looking for less expensive ways of getting that same result, or at least close to it. And really, I just don't have very good teeth. At least on top. Thank you orthodontist for putting a pallet expander up there which destroyed any enamel I might have had. Sometimes I wish they would have just pulled two teeth. Would have saved me a lot of torture during those crucial high school years.........