Buying guide

How to spot a fake deal.

A discount has two numbers in it. The price you pay, which is real, and the price it is compared against, which the seller chooses. Only one of those is a fact. Here is how to tell the difference in about thirty seconds, and what Dipp found when it checked its own records.

1. The percentage is measured against a number someone picked

“70% off” does not mean the product is cheap. It means today's price is 70% below a reference price supplied alongside the listing. That reference can be a price the product genuinely sold at last year, or a price it has never sold at once.

Of the 1,008 products in Dipp's catalogue whose reference price currently implies a discount of 5% or more, 103 are selling above what Dipp has recorded them typically costing — roughly one in 10. The badge is accurate. The saving is not. A separate, stricter test — restricted to products where both numbers point to a real discount, and counting only a 10-point-or-more gap between them — found the same pattern at a different scale; see the September reference-price study.

This is why Dipp stopped using seller reference prices as the basis for a discount when its own record disagrees. The methodology page sets out exactly what replaced them.

2. Prices go up before a sale, not down

The week or two before a big sale event is when reference prices get set. A price that rises in the run-up and falls back on the day produces a large, entirely truthful-looking discount. For the next Amazon fall event, Dipp keeps a separatePrime Big Deal Days price-history page so the event shelf can be checked against prices recorded before the sale.

Dipp has 539,944 recorded price checks across 5,934 Amazon.ca products. Comparing each product's price today against its own median in the fortnight ending two weeks ago: 14.9% of them (650 of 4,354) cost more now than they did then. 159 are up by a quarter or more.

None of that is proof of intent, and this page names no products and accuses no seller. It is simply what the prices did. The useful conclusion is narrower and more practical: a discount announced during a sale tells you nothing on its own about what the product cost a month earlier.

3. Some products just alternate between two prices

The pattern that catches people out most often is not a fake discount at all. It is a product that flips between a high price and a low one, over and over, all month. Whichever one you happen to see, calling it a discount is meaningless — the “sale” price is simply one of the two prices this product has.

A price history makes this obvious in one glance and is close to impossible to spot otherwise. If a chart looks like a square wave rather than a line with dips in it, wait: the low price comes back on its own, usually within days.

4. Learn the two shapes

Almost every price history you will look at is one of these. You do not need to read the numbers — the silhouette is enough.

A steady price that dips below its usual line, then returns
A real drop. The price holds a steady line, falls below it, and comes back. The dashed line is what it normally costs — the saving is the gap beneath it.
A steady price that steps up, then falls back to where it started
A step and a return. The price rises, sits high long enough to become the “before” price, then comes back to where it already was. Sold as a discount. Nothing was saved.

5. The only real test is what it cost before

Every check above reduces to the same question: what was this price a month ago? A seller's reference price cannot answer it. A screenshot cannot answer it. The only thing that can is a record taken before you went looking, which is the one thing you cannot create after you have decided to buy something.

You can keep that record yourself. Put the products you are considering in a spreadsheet, check each one every day, and write down the price. It works, and after three weeks you will know exactly what a fair price looks like for every one of them. It also takes three weeks.

Or let Dipp keep it for you

Dipp has been checking Amazon.ca prices in Canadian dollars several times a day and keeping every result. Look up any tracked product and you get the recorded low, the typical price, and a plain answer about where today sits — free, no account needed.

Set a price alert before a sale starts and Dipp will email you when the product reaches your number, with the history attached so you can see for yourself whether the “deal” is one.

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The thirty-second version

  • Ignore the percentage. It is measured against a number the seller chose.
  • Check what it cost a month ago, not what the badge says it was worth.
  • If the price alternates between two values, neither one is a sale.
  • A real drop dips below a steady line. A fake one steps up and comes back.

Dipp is an Amazon.ca price tracker for Canadian shoppers. It does not set prices, does not sell anything, and earns a commission from qualifying purchases as an Amazon Associate — which is why every claim on this page is one you can check against the recorded history yourself.