Cruising the listings on ebay I found this 350cc diesel Royal Enfield Bullet. A company out in Colorado promoting the use of biodiesel imported the bike and use it as a demonstrator.
This is obviously no hot rod, but on the other hand, it will run on biodiesel or straight vegetable oil, pretty neat. If you make your own fuel, you could run this thing practically free. This could be one helluva deal as long as you have plenty of time to get where you're going.