I've had people who would bite on the price of a $100 dollar bill being offered at $50. I swear they're out there.

Best thing to do with an ad you place for something you know the value of - Use the word: FIRM at the end of the price. This weeds out the riff-raff. Just stand stoically and stare when they offer you the "Shiny New Nickel" in their pitch. Do NOT budge.

Been there - Done that.