GSM World Phoen
Yeah I have one which I got to use in Europe and it works fine here with ATT on their prepaid no contract plan. Since it was an older model phone (designed for europe actually) it was more economical ($175) then buying the newer models($400+). Ive had no major issues with it and Ive had it over two years so far. I'm planning on taking it to bahrain with me when I go there which would be the third continent Ive used it on.
First thing you would want to consider is what provider are you with? If your with ATT and Tmobile its very easy to get an unlocked phone and switch in a SIM card Now it you have Sprint, alltel or Verizon you'd have to get a phone off ebay and then rig it somehow. Go take a look at
Howard Forums they have a lot of good information and I did a lot of research there. One of my other places I recommend you go take a look at is
GSM Arena they have alot of specs on specific phones and manufacturers. If your shopping Amazon actually has a decent selection of Unlocked phones, otherwise just google "unlocked GSM worldphone" and retailers will pop up. I tend to be a little wary of ebay since what you see is what you get and if somethings wrong those guys tend to not care.