TLD List - Compare Prices of All Top-Level Domains
Domcomp - No-nonsense domain price comparisons, updated daily
Tldes - Comparison of domain prices of 86 registrars. Data is updated every 4 hours.
NameSilo - Domain registration. That's it! And that's what makes it special.
Webhostingbids - Hosting Index, All top level domain pricing comparison, cheapest register, transfer and renew prices.
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.