How much would a used iPhone 3GS 16gb in good condition sell for?

I'm looking to sell my black iPhone 3GS 16gb that I bought in March. It's in good condition and works fine. How much money do you think I could get for it?How much would a used iPhone 3GS 16gb in good condition sell for?Unlocking it may or may not ad to the price. I would say not to advertise whether or not your phone is jailbroken so that it will get everyone's attention. Then when you have a buyer you won't have to worry if it's someone who wants a phone that isn't unlocked. Usually you won't get more money because most people know its extremely simple to unlock it, but make sure you DO NOT upgrade the ios to 4.0.2 because there is no unlock for it right now. A phone that's an 8 or higher (1-10 scale) can get you $350 min, a 6/7 about $320 tops but sometimes you get really lucky. If you're gonna post on craiglist make sure you post at least $30 above what you will go for and add "or best offer" to description. Nonetheless you will sell this phone in 24 hours or less, good luck!How much would a used iPhone 3GS 16gb in good condition sell for?i have a iphone 4 with a cracked back id trade.