The serpentine belt is due at 60K. It comes off and goes back
on as part of the timing belt service (so no extra charge for labor
should be expected). Timing belt takes a mechanic
about 2.5 - 3.0 hours to replace. The water pump is probably fine
and should be inspected. The tensioner is probably fine, too. I don't
see the need for an idler, either.

You've got about $90 worth of parts and three hours labor at the
70K service. Change the oil and do the other 10K service stuff for a
bit more.

Now, if you skipped the 60K service then it will be more since you need
to be looking at brake pads, brake rotors, fluid flushs (tranny and brakes) and all that stuff listed in the manual. The 60K service is typically
the expensive one and the 70K should come in around $300 (depending on
labor rates in your area) due to the timing belt.

By the way, I've noticed my (former) indy mechanic was more into
replacing parts like the water pump, tensioner, etc. then the dealer
ever was.