There are several places where you can find historical prices sold for domain names:

1. Domain sale history websites: Websites such as Namebio, DomainIQ, and Domain Name Sales allow you to search for domain names and see the prices they have sold for in the past.
2. Registrar’s sales reports: Some registrars, such as GoDaddy and Namecheap, publicly disclose the prices of domains that were sold through their platform.
3. Domain auction websites: Websites such as GoDaddy Auctions, NameJet, and Snapnames, provide historical prices of domain names that were sold through their platform.
4. Domain forums: Websites such as DNForum and NamePros allow users to discuss domain names and post historical prices of domain names sold on their platform.
5. Professional domain brokers: Professional domain brokers have access to a large database of historical prices of domain names that were sold, but it’s difficult to access this information unless you are a customer of the broker.

It’s worth noting that the prices found in these sources may not be the exact price that the domain name was sold for, as the prices may be hidden, but the data can give you an idea of the range of prices domain names similar to yours have sold for in the past. Additionally, it’s important to keep in mind that prices can vary significantly depending on the quality and uniqueness of the domain name, and the demand for it in the market.