I cant tell you much about pricing but my dad has a shop for mainly fleet work but I take my X there to do my work on it. This past week I replaced the timing belt and while I was in there I also did the water pump, some coolant hoses, all three of the drive belts, two idler pullys, and the alternator. To get to the timing belt you have to pull the radiator, this is why most of the time you will be replacing parts such as the water pump and thermostat.
I have a 2001 xterra se 137,000 miles on it.