STOCKWISEPrepared for less.

How we score

Every listing on Stockwise is compared with what that kind of item typically costs on eBay UK right now. The numbers below are the whole method; nothing is judged by hand.

The typical price

Each item belongs to a class (head torches, 20-litre water containers, portable power stations and so on). For classes where the title states a size, the comparison is per unit: pounds per watt-hour for power stations, per 1,000 mAh for power banks, per watt for solar panels, per litre for water containers. Other classes compare plain prices.

The typical price is the median over the last 30 days, taking one value per seller so that a trader with twenty listings counts once. New and pre-owned listings have their own typical price; a listing is measured against its own group. A typical price needs at least five distinct live sellers behind it. With fewer, the class's typical across every condition is used and the card says low data.

Some classes hold kinds of thing that are not priced alike: camping gas by cartridge type and size (butane cassettes, Campingaz pierce and Easy Clic cartridges, screw-thread canisters of about 100, 230 and 450 g), foil against wool blankets, mini against full first aid kits, generators and power stations by output, folding against rigid water containers. Each kind has its own typical price and is compared only with its own kind. A listing whose kind the title does not say is not scored. Multi-packs are priced per item from the pack count in the title ("8 Pack", "4 x 227g", "Pack of 12"); a listing of several pack sizes at one price with no count is not scored either.

The verdicts

Classes compared on plain price (torches, stoves, first aid kits and so on) are broad, so their bands are wider: a buy is under 70% of typical, fair is up to 10% over, and only more than 60% over is an avoid. A cheap torch is only a cheap torch.

A comparable listing is one of the same class and condition group whose stated size (watt-hours, mAh, watts, litres) is within 20% of this one's. Classes compared on plain price have no comparables: a cheaper torch is not the same torch.

Like for like

The typical price covers a whole class, from the cheapest to the best, so a gap against it decides a verdict but is not a saving. When we say a listing is cheaper, we mean cheaper than listings of the same thing: same class, kind and condition, a similar title, the same pack count or a stated size within 20%, one value per seller, postage included where it is quoted. "Cheaper than 5 of 7 similar listings, £12 to £16" means that. If fewer than three other sellers list the same thing, if the "similar" listings are more than half the class, or if their prices are more than three times apart, we make no claim at all. A kit's total follows the same rule and says how many of its items could be compared.

Auctions

Auctions are shown apart from the deals and never count towards a typical price or a 30-day low: a current bid is not a price. The suggested maximum is the price at which a fixed-price listing of the same kind would be a buy.

What is left out

Stockwise never lists knives or blades, weapons, self-defence sprays, crossbows, air weapons, medicines or iodine tablets, indoor combustion heaters, or fuel cans. A filter drops those before anything is scored, and the published site is checked against the same list at every price check; one slip and the site is not published.

Independence

Verdicts are computed from prices before any link is written, and the scoring code never reads which links are affiliate links.

Prices are read from eBay five times a day, and a listing is never shown once its check is six hours old: each one says when it was checked. They change; the listing on eBay is what counts.