I think a lot depends on what type of auction. Here, (Canada), at estate auctions, you sign up to get a placard with a number on it. When you bid, you hold up the placard. If you win the item, then at the end of the auction you have to pay for it, in cash or by credit card, for example. If you can’t pay for it, you don’t get to take it, and they add it to their next auction. And they will probably ban you from future auctions.
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