Domcomp - No-nonsense domain price comparisons, updated daily
TLD List - Compare Prices of All Top-Level Domains
Pricepeek - Compare prices of the same product across all Amazon locales
PorkBun - Porkbun is an amazingly awesome ICANN accredited domain name registrar based out of Portland, OR. We're different, we're easy, and we're affordable. Use us, you won't be sorry. If you don't use us we'll be sad, but we'll still love you.
The Mac Index - Compare Apple product prices in different countries
dofo.com - Domain search platform Dofo.com gathers all registered (350 million) domains of the world in a single place. Dofo also brings together all the domain names that are on sale, provides useful features, all completely free.