They wouldn't, because they wouldn't know how much to bid. People pay more on eBay because they see how much more they need to pay. The whole point of a Vickery auction is to eliminate this feedback. A tiny fraction of megawhales will overbid by an order of magnitude because they want the gadget at literally any cost - but the vast majority of people would underbid, specifically because scalpers haven't started selling it yet for inflated prices. The act of putting it on eBay itself increases how much people are willing to pay for it. The big winners would be scalpers, who, being both the professional appraisers and the market makers, are in the best position to bid well and are nearly guaranteed to resell at a higher price.