Think twice, or more, and buy once. There are always real, legitimate good deals to be had, no matter what you want. And at the end of the day you will be glad you waited.
But in the end you do lose out a lot, don't you? Most of the time I suspect. There is always a reason people are selling something for what seems a bargin price.
I remember when digital cameras first came out. Some guy in a bar (who I vaguley knew) was trying to sell an expensive camera for $50. Red flags went up all over the place. The first thought I had was, stolen. And I was right. He later went to jail.
Do some online research first, on whatever you are going to buy, and talk to family and friends. It's work the investment of your time. Impluse buying is seldom if ever a good idea.
Your going to have a hard time selling that anywhere. New phones are so cheap now. Why did you buy a second phone to start with? And really man, don't buy anything off that site. You know the old saying "If it sounds too good to be true"..
That's one reason I won't buy anything from sites like that. Too many people who will sell you anything, and you have little or no recourse if you get taken. I won't use Craigslist for anything. They have a horrible reputation.