Wikibuy - Find lower prices at other sellers while you shop on Amazon
Domcomp - No-nonsense domain price comparisons, updated daily
Honey - Honey is a browser extension that automatically finds and applies coupon codes at checkout with a single click.
Pricepeek - Compare prices of the same product across all Amazon locales
CouponFollow Cently - Coupons at Checkout is a browser plugin for Chrome, Firefox, Internet Explorer, and Safari that...
The Mac Index - Compare Apple product prices in different countries