Nice. I've been known to do that from time to time!
I frequent the estate sales and yard sales in the area. Most of the estate sales are run by professionals, and they do a fairly good job of making sure that they know the true value of what is being sold there. Often, I find that they are actually overpriced, but every so often something slips between the cracks.
Garage sales are a different story- I find lots of things at those that end up turning a hefty profit for me. My wife used to complain about my buying so much 'junk', but once she started seeing it turn a profit on things, she got quiet
One of the better 'hauls' was an antique viewmaster that I talked the guy down to $1 on... It was an old bakelite one, in it's original box, with all it's paperwork, accessories, etc. Best of all, the battery compartment was still sealed off, with instructions on how to load the battery, so it had probably never been used. I sold it on E-Bay for $150- Not a fortune, but when you consider that I only has $1 invested in it, Not too shabby
-Andrew