I am looking for a VW bus to buy and i have various questions. Mainly including where to buy one other than ebay. I also would like to know about what mileage they can take. Any info on this subject would be greatly appreciated.

Those vans changed a lot over the years. Early vans, from the 50's and 60's were underpowered and slow; with early models having as little as 36 hp to get them down the road. They got excellent mileage for what is essentially a minivan, but were too slow to be safe or useful on today's highways.

the later ones can go up to 65 mph but are a bit unstable at that speed. www.collectorcartrader.com is a great site for old cars.

Make sure to carry a ton of spare parts with you and make sure that the engine is getting a good supply of air to cool it down.