I don't like the idea of, basically, drawing the termites to you home, ie., the bait method. If they happen to 'leave' or not be there, then why encourage them?
A few of my neighbors have an Exterminator come around, I believe, once a month for $20 a visit. (That's $240 per year. So $300 isn't that far out of the way, and you may want to see if you can negotiate it.) None of them have any 'active' problems with termites. My immediate next door neighbor is the most recent 'addition' to the list of neighbors seeing an Exterminator on a regular basis.
So, I bet you're wondering why it is that my neighbors have had termites and I don't, including NOT having an exterminator? Well, I've dramatically reduced, and in some cases eliminated, the conditions in which termites thrive. My crawlspace is dry, My gutters don't leak and are functioning properly, my downspout water is being channeled FAR away from my foundation, and I've trimmed my trees, opened up the canopy, and moved / removed any vegetation that sits up against my house and deck. Essentially, by keeping the 'problem areas' dry and sunny, I have no termites. It saves me $240 per year. Sure, my 'lot' looks a bit bare but we traded that off for no termites and no annual bill. (Really, our lot just makes our neighbors' lots look overgrown. It's a relative comparison ...)
I can't say if the 'base fee' is a fair one but the annual fee, as I stated earlier, may be negotiable. My best to ya and hope this helps.