From the eBay help page:

If the buyer is still registered, please give the buyer 4 days to pay.

Okay, that sounds reasonable. You need to wait 4 days before taking any action against a user who hasn’t paid. In all of my auctions, I always specify that payments must be made within 3 business days of the auction’s termination, but apparently eBay is giving everyone a free 4th day.

Where things go bonkers is when you read how you have to resolve the situation once the first 4 days have passed. You open a case and then…

The buyer has up to 4 days to send a payment after the case is opened. During this time the buyer can also contact you to request a payment extension or make another arrangement. Of course you can agree to the buyer’s request, but you’re not obligated to make special arrangements.

So wait… no matter what I specify in my auction, any buyer can just wait 8 days before paying me. Here’s why that’s a problem: if the winning bidder waits 8 days, then decides not to pay, anyone else whom they outbid has probably already moved on. Heck, they could have paid and had it arrive in the mail before eBay lets you cancel the winning bid. So as a seller, I’m basically going to have to relist the item, wait another 7 days, then hope that this time the buyer pays, and that the auction sold for relatively the same amount.

Good to know that no matter what, you can always wait 8 days before paying for something you win on eBay.