Veblen goods are a special case that prove the concept. With a Veblen good the price paid is part of the demand: you want that Rolls Royce or Lamborghini or diamond ring because its expense signifies your social status. The demand curve then slopes upward: at higher price points consumers demand them more. You can still analyze them by supply & demand, but you just have to take into account the upward-sloping demand curve (which is not unlimited, BTW: Veblen goods still reach an equilibrium price point where supply reaches buyer's ability to pay, it's just higher).