eh... my Ex had that van. Was nothing but trouble.
If it has 100,000 miles on it, then i would say stay away. Get a "new to you" car. I bought my camaro in June 2005 for $4,700 with 58k miles. I have had ONE problem with it since and I've put 18k on it, done some performance mods and still runs great (and strong
As for how many miles you have left... that all depends on how well you take care of your cars. Also, when repaired, if you went to a GOOD mechanic (should be YOURSELF) or not. We don't get rid of a car until it is over 200,000 and not worth fixing. The last car we sold was a 95 Jimmy with 175,000. We sold it about a year ago and it is still running. A friend of ours bought it. But, at the same time, you can scrap a car at 70,000 miles.
All depends on how the maintanence was and how well repairs are.
EDIT: And by maintainance, i dont mean cleaning carpets, polishing tires... i mean engine flushes, transmission flushes, oil changes, filters, sparks and wires...