We moved into our house about a year ago, and soon after, we noticed what looked like "termite dirt" on our window sil. Thinking the house inspection missed that, we were mad. We called Terminix, and asked them to come out and see whether or not Termites had taken over. We're thankful it was only carpenter ants (which really aren't much better). At that point, we decided to sign a year contract. We are now actively keeping the nasties at bay!
Terminix comes out every 3 months (or more often- for free- if you need them). We receive their "basic coverage" and their "expanded" coverage. (Look on their site for more information). There has been a significant drop in bugs! (Bye-bye spiders, ants, and bees!) We pay a bit less than $500 for the whole year, though you can receive a 10% discount if you pay the full year up front, and another 5% off if you renew with them by signing a new contract. Remember that all termite inspections are free!