This has been posted on a few times before, so it's worth it to search for water pump-related posts.

The short end of it is that this is well within the grasp of a moderate DIY, mostly the hard parts are getting to a few hard-to-reach bolts and dealing with stuck bolts. Otherwise it's just long and kind of tedious.

1. get the shop manual, if you don't already have it.
2. Don't forget to replace the short bypass hose between the top of the pump and the block.
3. Don't put sealant on the water pump gasket, a little bit of grease to hold it in the groove while installing is fine.
4. Loosen the pulley bolts before you take the belt off.
5. The snap-on wobble extension really does save a lot of time, if you're inclined to pay the extra ~$50 for the tool. Even if you have all of the u-joints and extensions, it's still a hassle trying to figure out which combination of socket, u-joint, and extension it takes to reach each of the pump bolts.