Ban him lol. But if he's a great customer they'll wait up to 30 days for his pymt, unless you object of course...
There's a limit after which you can instruct the transfer rep to cancel for non-pymt...
Redirect the servers AWAY from Sedo while you wait since they won't present any offers to you in the meantime (if you have the servers directed to them), it also depends if you think $60 (meaning you're left with 10 meager bucks) is still ok with you, if you're havin 2nd thoughts then cancel the sale asa you can