Probably best scores for me on Ebay that come to mind is a really rare Washington Redskins pennant that was hidden. I have seen 3 show up on Ebay in 10 years of buying them. I do own one of the other 3 and figured I'd buy it and re-sell it if it was cheap enough. No one else bid on it but me....got it for $9.99 and it's probably a $250 pennant but has a little staining so I'm thinking $150-$200 easy. The 2nd was a hand carved Anri nativity set that I knew a lot about. Someone listed it with a BIN for $800. I immediately bought because I knew someone who wanted the stable bad and was willing to pay $1,500 for one. I turned around and sold him the stable for $800 which made him happy and I kept about $1,000 worth of hand carved nativity figures for myself.
"The farther we go, the more the ultimate explanation recedes from us, and all we have left is faith."
~Vaclav Hlavaty