I just replaced one last week on a 1998 Rav. So different model. The pump was original equipment and cost about $35 on Amazon. I had spent $700 three years ago and I was upset that the pump did not last longer. So this time I did it myself. It took me 14 hours the first time. Then I realized I made a mistake on the timing belt and ripped it all apart and had it back to together in no time (total time : 3.5 hours). The tricky thing on the 1998 is the motor mount that needs to come off before the timing belt covers could be removed. Those motor mounts are squeezed into an incredibly tight spot. Other than that, it was very straight forward. That said, if you need to do the timing belt, oil pump seal, tensioner, power steering belt, or any related parts; it would make sense to do these all together. The Toyota water pump gasket may have the rubber rim around the edges that creates a self sealing gasket. Those are very nice and worth looking for. My 1998 did not offer those gaskets.
No real surprises with this job other than finding out the last mechanic that worked on the car did not use the correct harmonic balancer pulley tool and had trashed the pulley.
I made a home made tool for loosening and tightening the crank bolt that holds on the harmonic balance. That was a big chunk of the 14 hours.