I've asked a few people to guess when they ask me how much I paid. Mind you, mine is an '07 that I bought a few months ago. Several folks have said $60,000. They don't have a clue as to what they are looking at, but it looks so damn good, they figure it must have been an outrageous price. Most not-BMW types guess above $40,000. I then tell 'em I paid well under what they think, as 2 seaters aren't selling well in this economy, and mine had been on the dealer's lot for 58 days. All of that is true, and I haggled to buy it for a price under blue book. An '07 is really very, very affordable when you consider that a new Mustang GT costs more than what I paid for the Z. I'd buy a 3 year old Z over a new Mustang anyday, and twice on Sunday.
Bottom line- it's none of their business. It's quite rude to ask such questions.
WiseGuy