wow
90k only on a 2001 highlander? great mileage

.
i would change the water pump as well because once the engines open its easy to change all the parts and any wear and tear from over 8 years of use. I'm recommending that you do all the maintenance or its going to be a headache just to replace the water pump, because they have to remove all the replaced parts just to get to the water pump. Plus if you go to another dealer or a "good local mechanic", they may inadervertantly damage, nudge or keep something off balance, which WILL result

in unforseen problems in the future.
Think of it this way, what your paying for is what the mercedes dealer charges just to do a routine maintenance (oil change, filter) on a mercedes benz c230
If you dont know a good local mechanic then head to your local toyota dealer and have it done. a good website that i found to see any complaints on past jobs is yelp.com, theres usually a posting of everthing from restaurants, carpenters, dealers and mechanics from previous customers, they're reviews are pretty honest

and to the point
at 90k I changed my water pump, timing belt, sbelts, coolant,spark plug, charged the ac, break pads, reset the brake and a bunch of other things. From a good friend of mine who worked at a toyota dealer at his place. he charged me the oem parts at a DEEP DISCOUNT and a case of corona
hope that helps