: The "winning bid" (hammer price) often doesn't include additional costs like buyer's premiums (often 10–25%), sales tax, and shipping fees.

: Research the market value ("comps") of similar items to ensure you aren't paying more than the item is worth.

: In online auctions, many buyers use "sniping" (bidding in the final seconds) to win without driving the price up early. Note that some platforms use a "5-minute rule" to extend the auction if a last-minute bid is placed. Comparison: Bidding vs. Buying Now

: Before bidding starts, decide on your maximum price and stick to it to avoid emotional overbidding.