One winning bidder emailed me and said "I don't want this anymore." Ok, you just wasted my 7-day auction, thanks. Another bidder simply did not pay.
Sellers get more on ebay because selling there is such a pain that a considerable premium is necessary to justify it. Maybe it's worth it for strange collectibles. For a commodity like an Apple computer? Never worth it. I would sell to Gazelle or MS and be happy with the huge discount.