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The water pump for around $75 and the labor time guide calls for 3.4 hours to complete the job. On this engine, the water pump is driven by the timing belt, so it's a good preventative measure to replace the belt at this time. The belt sells for around $80 and you'll need to add another half-hour to the labor. Labor rates vary from shop to shop, but fr a job of this type, a "fair" rate can be anywhere from $85-$125 per hour.
As for a DIY'er job- The skill level on this job is fairly high, and having prior timing belt experience is a huge plus. So, probably not the best for a DIY'er.