You'd be surprised at what's available over the counter at your local parts store. You just need to know what year and model of car to ask for. Many are rebuilt, but some are new.
Suggest looking for a mom and pop parts store that's been around for years in your local area. They may have parts thats been on the shelf for years, but many rebuilders can supply rebuilt parts.
If you don't have one in your area, this store has old farts behind the counter that can help you and they have quality parts as well!