I had the waterpump replaced recently on mine by my trusted mechanic (non-Ford). Total cost was $300 including taxes. Here is the breakdown of the cost:

New pump w/ metal impeller - $168
Labour (1.5hrs) - $90
Coolant - $10
+ taxes = $300

I asked my mechanic if the book time of 1.5hrs was sufficient, and he said they had no problems getting it done.

Black '98.0 GL V6/MTX, tints, SVT airbox (sans fender boot), stock muffler replaced with spiral racing muffler, A6 side markers, Cougar 16" polished wheels w/ bald 205/50/16 Yoko A520's, Mobil 1 5W30, Castrol SATF/Ford FM tranny cocktail, 9005 high-beam bulbs all around, re-aimed stock foglights