What type of driving will she be doing? Unless she's going to be driving long distances away from home, is there any reason to worry about the reliability of the minivan? If she's close to home and it breaks down, there isn't far to go to get back home. 18k is a LOT of money to spend on a perception of reliability.
We bought a 2000 Sienna a couple of months ago for $2000. It took me six months to find the minivan on Craigslist, but it was totally worth the wait. It has 165,000 miles on it, but I fully expect that we can keep it running for another 100,000 miles, or more. We've taken it on two road trips so far. I do have to admit, it's sooooo nice to have the space.