The effect is amplified by two factors:
1. When the product is hedonistic, anticipated pleasure undermines rational thinking, and anticipated loss of almost-real-already pleasure (brought up by the sales agent) leads to excessive risk aversion
2. Timing. To pony up a large sum of cash one has to go through some emotional upheaval, and the moment right after that is the moment where a person is likely still convincing himself how valuable the purchase is. Anyone who didn't convince themselves is not buying, thus all buyers are either indifferent (not enough money) or momentarily very attached to the product. Timing is very important here and commands 100% higher margins as demonstrated by the 2x different between in-store and after-market warranty costs.