Ringtones for Phones

Hi There. I’d like to buy an unlocked/ sim-free cell-phone in Manhattan or Brooklyn while I’m there to be used overseas. Probably a Sony Ericsson, but nothing too top of the line. I don’t want to buy it from some guy off the street, but rather from a reputable seller.

I know these phones are sold at full retail, but do you know of any shops/places where I could get a good deal on one without having to sign a contract?

Thanks in advance!