if you sell on ebay, be smart. take pictures with dates of everything in working order, take pictures of your serial number, the condition of the phone. Be diligent! Just incase someone tries to scam you . You can't be too careful.
Get tracking and possibly a signature when you're shipping
Technically I didn't make money, but I like to think that Ive made money off the two iPhones I've sold on ebay. Ive bought them on contract for 199, and normally make 200-300 on the phone on ebay. Im sure I could have gotten more, but I use Buy it now and they normally sell within the first day I have it posted.