Just based on the rust I can see, I'd want to take a close look at the entire undercarriage, before buying.
To me it looks used hard, and put away wet. The Highlander package is/was overrated anyway. Basically you got a fake hood scoop, and 1" taller springs, that have sagged by now anyway.
I'd look for a well taken care of V6, 4wd, 5-speed, E-locker equipped '96-'00 4Runner closer to home. That was a fairly common option package on 4Runners sold in Utah, back when these trucks were new on Dealer lots.
I'm in Utah. I see a lot of sports on the road, very few for sale.
Yeah, that's my biggest concern. I've asked him twice about the undercarriage and he seems not to want to answer. And to make things worse I'm about 1200 miles away, so if have to take his word for it and fly up there... Might be worth passing on?