METHODOLOGY
Prices need context.
Shopcalypse displays only stored, validated observations. Comparable offer types are kept separate, averages are calculated from like-for-like prices, and a deal label requires at least three observations.
Comparable prices only
A buy-box price, an Amazon retail price, and the lowest new landed price can each describe a different offer. Shopcalypse selects one comparable price kind for a history and does not mix it with used offers, subscription discounts, member-only prices, coupons, or crossed-out reference prices.
Shipping and currency
Landed prices include item price plus known shipping. Amazon.com observations remain in USD and Amazon.ca observations remain in CAD; values from different marketplaces are never merged into one history.
Deal classifications
Shopcalypse needs at least three comparable observations before labeling a deal. A great price is 10% or more below the recent comparable average, a typical price is within 10%, and an above-average price is 10% or more higher. When recent history is unavailable, the page says so instead of inventing a conclusion.
Freshness and limitations
Every accepted observation is time-stamped and product pages show the latest check. An observation is evidence of a price at that time, not a guarantee that the same offer is still available. Always confirm the seller, fulfillment, condition, shipping, and final total on Amazon before buying.