Bunch of RTD buses about to hit the auction block this Wednesday here in Denver.
Don't quote me, but these Orion V's tend to sell in the $1500-$2500 price range.
Word of caution, don't buy these sight unseen. Some are okay, some are really rough, and mileage doesn't seem to be the indicator of condition. I would definitely go to the Auction's physical site, kick the tires, see if you can hear them run, etc.
10.8 liters HAS to have great fuel mileage, lol. I don't know what their top speed/cruising RPMs look like, but I see them on the highway all the time. They'll do at least 55, probably governed around 62mph, but they're not the planetary-driven buses like the mall rides use (max out around 40mph).
If you give this a shot, good luck to you!
The link: Roller and Associates, Inc.