Fallacious belief that something must be good because you shelled out a lot of money for it. From the joke about two nouveau-riche types who are standing next to each other at a party wearing identical ties. One says, "I got this tie for five hundred Euro". The other says, "That's nothing. I got mine for at least two thousand Euro." Not to be confused with the principal that if you buy cheap, you get cheap ... for a yuppie's necktie is never cheap.
Don't spend a hundred grand on a car. Only those who can't see through the yuppie's necktie fallacy do that.