Don’t fall for “strikethrough prices” or impulse buying during sales

Cost: Zero monetary cost. The trade‑off is that you might miss out on some genuine discounts. You’ll need to keep track of the regular prices of the items you buy most often. The real challenge is resisting the urge to stock up on the day of a sale.
In plain terms: When judging whether something is cheap or expensive, people rely on the first price they see; later adjustments rarely make up for that initial impression. Thus, a claim like “original price 999, now 499” makes us systematically overestimate how much we’re saving. By regulation, the baseline for a discount should be the lowest price at which the item actually sold in the seven days preceding the promotion; the crossed‑out price isn’t necessarily a real transaction price.
Benefit: Human judgment is anchored to the first price encountered, and subsequent corrections are usually insufficient. Consequently, statements such as “original price 999, now 499” inflate our perception of the discount amount. Official rules require that the reference price be the minimum actual sale price recorded in the same store during the seven days prior to the sale; the discount percentage must be calculated against that figure. The price marked through may never have been charged in reality (China, effective 2020).
Evidence grade: C
Sources:Tversky A, Kahneman D (1974). Judgment under Uncertainty: Heuristics and Biases. Science 185(4157):1124-1131. https://doi.org/10.1126/science.185.4157.1124；国家市场监督管理总局 (2020). 规范促销行为暂行规定（总局令第 32 号，第二十一条）. https://www.samr.gov.cn/zw/zfxxgk/fdzdgknr/fgs/art/2023/art_cae53a080be2401e8f91c6d6291539f8.html
Notes: The anchoring effect is a finding from laboratory studies; no one has quantified exactly how much money consumers lose by over‑buying. There are also hidden costs: items may expire, they take up space, and we tend to use them more simply because they’re on hand. Only purchase in bulk when all three conditions hold: a long shelf life, a definite need for the product, and a price genuinely lower than its usual cost.