Looking for a credit score service to watch my score monthly

Has anyone done research on credit score watching services? I’d like to find a service that doesn’t cost an arm and a leg, but will allow me to watch from month to month, and view over different ranges of time. Is there anything like this that will do it for 1 of the 3 credit reporting services.

Better yet, for 3 of the 3? How about for 2 different individuals (spouse etc…)