I assume when you say airlines wanted $150 to $175, you are meaning 1 way. Alaska Airlines, which fly's from Philly to Missoula, currently charges $75 one way ($150 round trip). Yea they aren't direct flights but it proves my point; a little research shows cheaper options than what I keep hearing repeated. Its good we have so many options though including driving to the start/finish of a loop tour, taking the train (yes you don't need to box a bike anymore on a lot of Amtrak routes), flying with your bike (some people like foldable bikes just to avoid fees), or shipping. What works for one person doesn't work for another. The important thing is to enjoy the trip.