the polyrib belt replacement is certainly super easy - i'm not mechanically inclined but had no problem doing it myself.
i have not replaced the water pump or thermostat myself. i'm not sure if i will do it or take it somewhere to be done, but pedro has a good writeup on how to do it - as well as how to do a lot of other projects.
i will say that through this forum as well as pedro and mike focke's site i have gained enough knowledge and confidence to tackle some other jobs - namely replacing the alternator, spark plugs and doing my own oil changes. my last oil change i went to a local dealership and "rented" their lift for $11. was a lot nicer than having to lay on my back in the driveway.
the quote for the thermostat is pretty much what i have been given ($359.97 parts & labor).
http://www.pedrosgarage.com/Site_3/Replace_Water_Pump.html