Howard's forums
I sold mine a few weeks ago. Went smoothly.
Didn't have to do anything over the phone. I needed the original personal full name and email address he had registered with AT&T (if they don;t have an account, then yes, you may need to do some over the phone).
There is a section when you log in to transfer billing responsibility. You enter that person's info, he receives an email, accepts everything, and you are done. They WILL NEED to get a new sim (or you can send your old one). I thought that was kind of stupid... the line was in his name but still active in my phone...
As far as pricing, it has dropped; unfortunately AT&T's unlimited data isn't really that great anymore now that they have introduced the 10GB share plan (and once you factor in throttling). There are lots of hopefuls on eBay still hoping for $300+ BIN. Most sell for about $200, maybe a little more. I sold mine for $150 as I wanted it to just be bought so we can sign up for new lines. After factoring in eBay fees (versus me not having to pay them) it worked out pretty well. You could maybe hold out for something between $200-$250, but then consider how long you might wait; this might put you into another monthly bill, which is money you could be saving by selling it for a bit less and hopping over to the new plan.