..................look with only a 500K budget yr simply asking too much. Do yourself & the Co. a fav, forget the MU-2. Best go back to the drawing board & make the required rwy length & sector lengths fit the plane, not make the the plane fit into where it simply can't go ! The B200 would be perfect in most ways but obviously way off the mark money wise. Casa 212?............yeah might work, but also engineering support & spares would also be an issue.............there's a whole gammit of things to consider other than having $500K burning a hole in ones pocket!:-)
Keep researching, there's a loooooooong way to go for you, don't get dissheartened, to every problem there's a solution:-)
Capt Wally:-)