Absolutely, rach -- and you can make more money, too.
Run it the same way, but include a note in your auction rules that says something like: "we reserve the right to turn any highly-sought-after silent auction item into a quicky live auction."
Then, on those last couple of items, instead of watching folks fight -- you pick up the sheet, stand on a chair and do the "do I hear $xx?, going once..." thing. It's fair. And you'll make more $$.
That tip and tons more are included in our complete Auction Toolkit available here:
http://forms.ptotoday.com/store/product.html?id=1004
Good luck,
Tim
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