I made some photos from the various VW campers I saw in Germany
and put them up on:

http://www.cs.rochester.edu/u/jag/vw/
(click European T3's)

Generally, for T3 Westies, high milage, early 80's ones start
at 2-3000 Euros. Decent mid 80's ones can sometimes be had
from 4000-5000 Euro, and well kept late 80's early 90's
are 6-8000 Euro. Due to the German winters and road salt
every T3 I saw had some rust, but on the better ones it was
still in the surface rust stage, so could be cured w/o major surgery.

T4 campers come in two distinct price categories. The 91-95's
have old style TD engines and are around 8000 Euro, while
the 96 and later ones with the both fuel economic and
stronger TDI engine are from 15-20,000 Euro for older,
and up to 30,000 for recent ones.

Martin