I recently started a watch list of Mac Pro available on eBay to get some idea of the going prices of 2009/2010 models. Then I stumbled on this completed transaction. If I remember correctly, the seller had a Buy It Now price for $1695. Instead the winning bid ended up at $5100. I know sometimes people overpaid in the heat of a bidding process, but this is just crazy for a 2009 machine. Can someone explain what's going on with this transaction?