Posted By:
ramramDid she make you watch "The Graduate" with her? 
My best was a purchase of an oversized (11" x 15") albumen image of the 1884 Columbus team. Extremely, rare in that large of a size. The seller had no idea who the team was. Got it for peanuts.
My worst was selling a dozen Old Judges for $250 about 8 years ago. Thought I was making out like a bandit since I got them for $5 to $10 a piece. People around the midwest just didn't know or care about 19th century cards back then. Luckily I kept the best cards.