How much do domains cost? Is that included in Domain Finder?

Domain Finder is a one-time fee for the naming work: availability checks, scores and brand reports. Registering a domain is not included. It is a separate charge when you decide to register a name.

The price depends on the extension (.com, .io, .co and so on). You can see registration, renewal and transfer prices for every extension at /domain-pricing, and the exact amount is shown again at checkout before you pay. Prices can change, so the amount at checkout is the one that counts.