

DomComp.com is the best for this. Comprehensive. Easy to use. They only usually go by published prices. The publish new regs, transfers, renewal prices per registrar. So you should check with the registrars to ensure they don't have any specials running. Especially for non .com. Also you might be on a higher tier with a particular registrar, ie NameSilo, Fabulous, etc.
But I wouldn't switch registers for pennies. I'd find a registrar you like, and stick with them, provided they are in your price range.