As of last year, you could pay by check at the end of the auction for all your items and still pick them up right there. The choice is either pay sales tax right there, and pick them up, or don't pay sales tax (but DO pay shipping & insurance) and have them mailed to you (assuming a non-Nevada mailing address).

This applies to the majority of bidders who run a tab for the entire auction. Alternately, you can be a "cash" bidder and pay for each auction lot with cash immediately after the lot closes.