can you post you ebay selling page so I can see how you advertised it please..... that will make all the difference ....
the problem is with buying stuff over the net (this is mainley new) you have a 14 day cooling of period and if you have a problem you can send the good back for refund.
You should say to him thats fine if there is a problem you will recieve a refund if the phone is in the same condition that it was advertised in, like you say next to new.
If the phone is no longer in the condition as you sent it then you will not recieve a refund.
If I can see your add I might be able to help more, if you put in the add, the item was sold as seen and basically saying it was working and is next to new at time of sale then you should be ok
But its really shit the buyer is always protected more