this, I would always give people at least ten days or so to respond and pay. people have other things that pop up and sometimes it just slips by. not always but sometimes, and they could be waiting for a paycheck .
if you run a sale and need the money in 30 seconds, you probably should not be selling comic books to make ends meet or pay bills. there's probably a bank down the street to get a loan from.
And wouldn't you look through the thread and check to confirm who posted I'll take it to confirm who bought the book ...
and then quote the and mark the item sold. its tough right.