As I'm sure a lot of other people are attempting, I want to sell my iPhone 3GS to upgrade to iPhone 4. After posting to craigslist and doing some internet research I found this site: http://www.cashforiphones.com/ I'm not sure if this site is a scam or not. They offered $355 for my iPhone 3GS 16gb, which seems kinda high. http://www.gazelle.com offered $198. How it works is they send you a prepaid box which you put your iPhone in, and ship off, and then they pay you in either a check or paypal. So, scam or not?