In reply to your question regarding speed limits in MT...the answer is yes.
They caved to the federal governments blackmail to withhold highway funds if they did not pass speed limit laws -AND- seat belt laws. Property, if not already owned by the government, was very expensive as was housing. A few "movie stars" moved in & apparently ran prices up on everything except wages, according to the locals. There was a thread here yesterday discussing another law about to take effect- no drinking & driving.
Depends on what part of Montana you're talking about. The (flat, treeless, ohmygawditsfriggincold in winter) eastern half is still affordable.