88 chevy pickup 4.3 L v-6 130,000 miles

well that depends on how much an hour he's charging.. and how many hrs(about 2-2 1/2 hrs)?? ask him what he's charging for water pump?? check out this link for pricing
remember that his price is going to be more.. but make sure he's not overpricing it... hope it helps..

I know it's difficult to say for sure...

I know that I can do a water pump out and in much quicker than 2- 2 1/2 hours and I'd gladly fill my day doing $300 water pump jobs. BUT, I don't have his overhead so it's hard to say. And I do have have torque wrenches/metres in inches and pounds and all extensions and angle bits.

If your not comfortable doing the job yourself (properly!!) Then get a second or third quote. Most shops will just look in the book for the job info and time needed to do it and give you an out of book quote even over the phone. Atleast you'll have some idea of the going rate. Make sure you know whether your getting a brand new water pump or a rebuilt in the quote.