Or the second seller got $100 too little. Really, it's a bad way to look at life. Yeah, I too get pangs when something goes on sale the day after I buy, but that's life. It was worth what I paid when I paid.
Well, that's the point of an auction. ;-) Still, to the sap, the widget was simply worth more than it was to anyone else. Yes, that's one reason I really don't like auctions.
I'm not good at estimating the worth of used stuff. I'd rather buy new, even if it does cost a little more. There's also the issue of not knowing if the widget is functional.