The Antiques Roadshow just finished with a woman reacting to finding out her painting was worth a load of money by uttering something that required an approximately one-second bleep. I'm surprised that doesn't happen more often. Finding out that you could pay off the mortgage by selling Grandpa's old table could make anyone's tongue slip.
Many of the estimates on there amaze me, or more accurately the fact that somewhere out there are people who collect some of that stuff. That said, there have been a couple of things that I would almost buy if given the chance. The viewfinder from the camera that John Glenn used on his first space flight comes to mind, as does a drawing by master animation director Chuck Jones (an interesting combination now that I think about it). It's worth noting that both of those were fairly reasonably priced. Most of the time I can't imagine spending the kind of money quoted on there, even if I had it.