J,
I haven't really had any major mechanical problems with mine (knock on wood) and she just turned 83,500. Isuzu is getting out of North America so we might run into parts issues in the near future, but for now everything is OK. Merlin with St. Charles Isuzu is our go-to guy on this site for parts and advice. Great guy, give us a discount AND free shipping.
Most Isuzu dealerships (if you can find one) have never seen a VX so finding a local mechanic that you trust is the key. The VX is basically a two door trooper with fancy body panels so finding mechanical parts isn't really a big deal. The body panels, on the other hand, are getting rare so just try not to hit anything.
Some of our engines do tend to eat oil so you have to stay on top of it. Most of us check our oil at every fill up and top off accordingly. Other know issues are; the stock CD player does tend to give up the ghost and eat CD's, and the windows start to stick and don't roll up well (but a member here has a fix for that). Some of the other issues are slipping my mind right now so hopefully some others will chime in.
If you take care of it the VX should last you a LONG time as a few members have well over 100k miles on theirs and there may be one or two at, or over, 200K.
Good luck on your search.
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at or repair."
-Douglas Adams, Mostly Harmless