How much should I budget for regular termite prevention per month?

I’m in the process of buying a home and am trying to work out my monthly expenses. There is currently no termite issues with the home, and I want to keep it that way. So what am I looking at in terms of the cost of regular prevention? The home is in a wooded area of Richmond, VA if that info is helpful.

I’ve looked at some of the big name services, but they seem kind of pricy. I’m just looking to cover basic protection for a home that’s never had any problems.