Where could you buy one??
Best place to try for a vehicle like that is either craigslist, which is simplified down to location, or ebay.
One of the best spots to find a bus would be search the classified's of www.thesamba.com there are always lots posted for sale there as well as a wealth of knowlege in the forums.
i agree thesambe.com is a very good spot
Looking for a Used Microbus in your area?CarGurus has thousands of nationwide listings and the tools to find you a great deal.
Search Volkswagen Microbus Questions
Volkswagen Microbus Experts