That's true, good buses don't last long. It sounds like you're looking mostly on craigslist, and those people are generally re-sellers trying to double their investment. If you're looking all across the country you're also looking at buses from the rust belt.
My bus, "I mean van," has 169k on it and you can still see the factory writing on the frame. That's how rust free buses are on the left coast. I think you're needing something like a Colorado bus with good heaters, drive line retarder and auto chains.
I can understand that you would want to drive the bus home, but remember how that is a difficult drive when you do know and trust the vehicle. I know the barge takes a month but at least it gives you a fair chance at working on the bus on your own time and doesn't leave you stranded on the side of the road in an au-natural bus. Unless you plan on buying a bunch of tool to take with you on that first long drive I'd try to work around it until you are sure you have all the kinks worked out.