How to check a product’s price history and spot a real deal

Since the Omnibus directive came into force, every shop announcing a discount must show the product’s lowest price from the 30 days before the promotion. It is the simplest honesty test: compare the promotional price with the omnibus price, not with a crossed-out "regular price" that the shop can set as high as it likes.

The omnibus price has a limitation, though: it only covers the last 30 days. If a shop raised the price five weeks before a sale, the 30-day lowest price will not reveal it. That is why, for pricier purchases, it pays to use tools that track prices over many months.

• CeneoPoland’s biggest price-comparison site shows a price-history chart for most popular products and lists prices from many shops at once. You can also set an alert for when the price drops below your threshold.
• KeepaA browser extension for Amazon - it draws a detailed price chart from the moment a product went on sale and lets you set price alerts. Useful when you compare Polish shops with Amazon.
• AliPrice and similar extensionsFor AliExpress there are extensions that track the price history of a specific listing. That matters, because on Chinese platforms "promotional" prices tend to come back every few weeks.
• Wishlists and the cartThe simplest method with nothing to install: add the product to favourites or the cart and wait a few days. Many shops and apps will notify you themselves when the price of a watched product changes.

The most common trick looks like this: the price rises a few weeks before a big sale event and then "drops" to the level where it was before. On a price-history chart the manoeuvre is visible instantly - the line looks like a step up just before the promotion.

The second trap is comparing the discount with a manufacturer’s suggested price that nobody ever paid. If a product has cost 30% less than the list price since launch, a "-30%" discount is no bargain at all. A price chart and a quick comparison across a few shops settle it in seconds.

Price history also reveals recurring cycles: electronics get cheaper when a new generation arrives, seasonal gear after the season ends, and the biggest real reductions appear around major shopping events covered in our sales calendar. If the chart shows a product regularly dipping to a certain level, that level - not today’s badge - is your target price.

• Set your target price based on the chart before the sale starts - in the heat of a promotion every discount looks like a bargain.
• Compare the final price including delivery, not just the product price - especially for cheaper purchases.
• For products sold per piece or in multipacks, calculate the price per unit, litre or kilogram.
• Set price alerts well in advance - the best deals on watched products often appear outside the big promotional events.
• Don’t be guided by the percentage alone - 15% off an honest price is often better than 60% off an inflated one.