Sales of Motor Vehicles on eBay are subject to different rules. You do not pay a "Final Value Fee" but rather a package up front that eBay gets the money for whether it sells or not. Relisting would result in a new fee for the new listing. And sales are not binding, either party can walk away, due to control of Motor Vehicle sales by the individual states. I think you can still cancel for non-payment after 4 calendar days to settle the status of the transaction (e.g. to safely make a Second Chance Offer, see below), but it likely does not affect the buyer's buying status.
I don't know whether Second Chance Offer applies to Motor Vehicle auctions. Check in your list of sold items to see if there is a link to send an SCO to any of the losing bidders.
