I've bought cell phones on ebay a few times, but it has been 5 or 6 years since I have done so. The biggest things to look for is to make sure it is a phone that works on the Sprint Network. Second, the EIN must be clear. The one issue I had, was when I bought a phone that didn't have a clear EIN (meaning it had been deactivated and removed from someone's account). I got a phone that was not clear and could not activate it. Fortunately, the seller was honest and worked with me to clear the EIN (he was selling the phone for a relative who had not taken the necessary steps) and I was able to activate the phone eventually. The problem is there's nothing you can do to verify these two points prior to receiving the phone. My advice is to buy from someone with impeccable feedback and a solid return policy in case you end up with a dud phone.