The 90-day average method, step by step — sixty seconds before you buy, instead of regret after.
As an Amazon Associate I earn from qualifying purchases. We do not track prices or send alerts — the price that applies is the one Amazon shows when you open the product.
Never judge a price against the crossed-out list price beside it. That figure is chosen by the seller, and it commonly rises in the weeks before a sale so the discount looks dramatic. Judge against the product's average selling price over the last 90 days instead. Averages are built from what people actually paid, so they are much harder to dress up.
The verdict is simple: today at or below the 90-day average is usually a fair price. Today well above it means the same product was cheaper recently — and very likely will be again.
Open the product on Amazon. Use the price you would actually pay — after any clip-on coupon shown on the page — and ignore the struck-through figure entirely.
The ASIN is the code in the Amazon URL after /dp/ (it also appears in the product details). It is the key every price-history tool uses to identify the exact product — model, size and version included.
Paste the link or ASIN into a free price-history site such as CamelCamelCamel. You will see a chart plus three numbers that matter: the current price, the average, and the lowest recorded.
This is the whole judgement. At or below the 90-day average: fair. Well above it: the chart is telling you the price regularly comes back down.
If a major event (Prime Day, Black Friday, Boxing Day) is near and the price is above average, waiting is usually free money. If you need the item now and the price is within its normal range, buy it and stop watching the chart.
Compare today's price with the product's average selling price over the last 90 days. At or below the average, the price is usually fair. Well above it, waiting usually pays. The average is hard for a seller to fake, unlike a list price.
Free price-history sites such as CamelCamelCamel chart Amazon prices and show the average, the lowest recorded price and the current price. Paste the product link or its ASIN (the code in the Amazon URL after /dp/) into the search box.
New or rarely sold products may have thin history. Then compare the same model across two or three retailers in your country, and check the sold-by and warranty details carefully before deciding.
Not always. The lowest price often happened during a one-off event or a pricing error. The 90-day average is the realistic yardstick; the lowest is a bonus when it appears.
The companion guide covers the rest of the purchase — sellers, coupons, returns and Canadian warranty traps:
