Yeah, $400 is about average for just the pump.
Here's a breakdown of what you should expect to pay at most shops:
Pump $89
Coolant $36
Labor $210 (3 hours @ $70/hr)
Misc. $30 (supplies, disposal fee, taxes, etc.)
That comes to $365. Obviously, prices for parts and labor will vary.
If you add a new timing belt and crank sensor (highly recommended), you should figure on about $500 or so total.
You can do it all yourself for about $200 (including the t-belt and ckp). You have to remove the tensioners, the crank pulley, crossover tube and timing covers.