1. Get the one with everything fitted, spares are never easy.
2. Usual car buying stuff, listen to it start from cold, check for leaks, smoke etc. Operate all the switches and levers and make sure everything works - diffs and low range too. Look for signs of extensive off-road abuse, even a Pinz will be in better condition if it hasn't bounced off every boulder on the training area.
2. Don't fret too much about bodywork - there may be some rust in doors, footwells, battery boxes etc, but it should be minor and relatively easy to repair, compared to fixing other things.
3. Higher mileages aren't a big worry, engines are comparatively easily to get parts for from VW. Assuming they're manuals the gearshift is always fairly agricultural but shouldn't balk or grind. Autos - check for no/lazy upshift from 1st when cold, worn out park brake, harsh/slipping shifts. Big miles may mean the rear diff is getting tired, listen for excessive whine from the rear at speed.
4. Check function/condition of rear air suspension closely. Disconnect the level control arm and push it fully up, run engine above 1800rpm and check airbags inflate after ~30secs.
5. Junk the bargrip tyres and riot protection screens.
6. Post directions to where these pictures were taken immediately
I'm bound to have forgotten loads of things, hopefully others will be along with their comments soon...
Tom