You did not mention what species of termites, you state, or the type of guarantee you were offered. Orking ususally adds one or two years of renewals into their upfront price when you finanace their treatment cost. You did no mention whether or not you were paying cash or financing.
Regaurdless of the details you omitted, I would venture saying you could get the same job with an equal guarantee less expensive with most other companies. Pick a good medium size company with a good local reputation ask them for a free inspection and quote if needed.. Try asking your neighbors about their termite services. I write extensivly about this in my Homeowner Guid to termite Control at http://TermiteMD.com , go ther for a lot more information.