PricelessPsychology showed some of the weapons commercial vendors use against us. Below I'll start a list of defenses we can use to thwart their evil intentions.

• How much does it actually cost?
  Convert the dollar cost to units of something you like. E.g. that fancy dinner will cost me 15 bottles of beer; am I willing to trade you 15 bottles of beer for that dinner?
• What alternatives exist?
  Most items we want to buy have close substitutes. Ideally, we want to enumerate all of the possible alternatives, and compare their costs / benefits.