The SigPath extension

SigPath's check, right on the shop's page.

1Add itTo Chrome or Edge, once.
2Shop as usualAmazon, AliExpress, OTTO, MediaMarkt, Saturn.
3See the checkPrice vs eBay, red flags, the best deal.

On every product page: the check appears at the bottom right.

On Amazon's results: Check with SigPath → under every price.
Any other shop: click the icon, then “Check this page”.
Your choice: sharing Amazon prices is off until you turn it on. What's shared

Install it

In the Chrome Web Store soon. Until then:

Download SigPath from GitHub (Code → Download ZIP), unzip it.
Open chrome://extensions, turn on Developer mode.
“Load unpacked” → the extension folder.