Here's a video, one of several regarding the timing belt replacement.
Also, here's one place that sells a timing belt replacement kit,
http://www.1aauto.com/timing-belt-kit-with-water-pump-gates-tckwp329/i/gaeek00013?f=481793&y=2003&utm_campaign=gb_csv_br&utm_content=EEK&gclid=CMOM7rHGhcYCFVKPHwodNYYAJw
As you can see, the kit also includes the water pump and seeing that it's driven by the belt, it makes sense to,get a replacement.
Now, the parts are around $200 and can be found for more or a bit less. The unknown in your case is labor. Shops calculate labor in basically one of two ways. There's a book rate which can be looked up in something like Mitchel and that's the estimated time to complete a job. That's pretty common because if ouve got a skilled mechanic he can do the job in much less time. So the owner of the repair shop only pays the mechanic by the hour while you're billed for the book rate.
Then there're some places that bill you for actual time. Only by asking can you know how yore being charged.
One thing to look for is that some places will look to nickel and dime you. Let's say there are separate hourly rates for a timing belt replacement, a water pump replacement, and a tensioner replacement. Well, each of these procedures requires the same basic steps - disassembly of the front to gain access and removal of the timing belt. Now, they're not going to reassemble it each time but they may bill you for it. Only way to tell is to ask questions and look at the estimate.
Also, you're going to pay list prices for the replacement parts while the mechanic gets it a discount. My suggestion would be to make some calls to various places looking for an estimate. Don't accept the answer, well we can't tell because there may be other things wrong. Get an estimate or move on. Then with a list of several places, search them on the web. Maybe Yelp has some feedback.
It's not really a difficult job but it is tedious and requires attention to detail.