Shop Flicker And Find — Finding discounts and | shopflickerandfind.com
A discount is the gap between today's price and what the item actually cost last quarter — the chart, not the banner, shows that gap.
A discount is a gap between two numbers: today's price and what the item cost before the sale. The banner supplies the first number and invents the second; the price history supplies both. Price-history tools such as Keepa and CamelCamelCamel chart a listing's price over 90 days and longer, and that chart is the reference.
Reading the chart takes three passes. First, find today's price on the line. Second, scan the previous quarter: the '50% off' claim is checked against the price the item actually had in that period, not against the crossed-out anchor on the page. Third, look closely at the weeks just before the sale began.
On narrow screens, swipe or scroll the plate sideways.
The pattern that matters is the pre-sale lift: the price steps up shortly before a promotion, then 'drops' during the event to roughly where it sat all quarter. On the chart this reads as a spike followed by a return to baseline — the advertised percentage is measured down from the spike, so the real saving against the quarter's typical price is far smaller.
Pack sizes need a different instrument: unit price — price per kg, litre or 100 units — is the only fair way to compare them, and the EU requires it on prepacked goods under Directive 98/6/EC. A large pack carrying a coupon can still lose to a smaller pack on unit price, and the chart will not catch that.
The check does not end at payment. Most retailers advertise price matching only for 14-30 days after purchase, so a drop inside that window is recoverable: keep the order confirmation, re-check the listing within the window, and claim the difference while it is still open.
Further reading