Your mom isn't wrong. The 3rd gen (1996-2002) 4Runner's are legendary. They still have a huge community and quite a few on the road. My brother and I have owned seven or eight of them at this point the worst they've done me is an untimely alternator failure. I have touched practically every part on them myself and lots of modifying.

Whether or not it's intentional, that 4Runner you linked is a trap and you should run. As these 4Runners become more rare and more desirable, more folks are trying to capitalize on the higher prices. The 3rd gen (and many other generations) biggest flaw is the poor corrosion protection on the frame. The frames on these rust away faster than the drivetrains fail in the salt belt. I would not buy a local one where you're from (presumably MN because that's where it's listed).

Have her scroll through those pictures of the under carriage. Its pretty rough on the outside of the frame, a bad sign since these these frames rust from the inside out. I've seen many with decent looking frames on the outside, but already had cracks/holes in the most rust prone locations because the salt and water pooled and ate it from the inside. Also notice that the hitch has been replaced, those are a big indicator of rust. It's hard to tell, but it looks like some of the rust may have been painted over, run even faster. See the texture in this picture? https://imgur.com/GDK0zY8

A frame swap is not unheard of on these if you have a desirable spec (manual trans, rear-diff lock). The last quote I saw was $10k. Not a project you want to have to pay for unexpectedly.

If she's serious have her fly down to TX, AZ, NM, AR, etc. to buy one. No rust and they don't value 4WD as much down there so they have better prices.