Example of a non-binding bid:
Mary lives in California and is the winning bidder on a car on eBay Motors listed by a dealer in Maryland. Upon checking the paperwork, Mary learns that the car doesn't comply with the emissions requirements of California and can't be registered there. Mary is not obligated to purchase the vehicle.
Example of a binding bid:
Steve is bidding on a new rug for his living room and he wins the auction. Later he finds out that the rug isn't big enough to cover his floor and he wants to back out of the sale, claiming the bid was non-binding. Because the rug wasn't listed in a non-binding bid category, Steve is obligated to pay for the rug.
参考:
http://pages.ebay.com/help/policies/non-binding-bid.html