The 90k service runs anywhere from 300-450 depending on where you live and who does the work (dealer, etc). The T-belt replacement will be an additional 450-600 on top of that.

If you're price checking make sure you comapre apples to apples, lots of places try to reel you in with a low price then start into the job and try "upselling" the balance belt/seal and water pump.

Do not go to Firestone type places, cheap parts and a lot of ignorant techs, not stupid, just ignorant (incomplete knowledge) no offense to anyone here who may work there.