I'm far from an expert, but my observation has been that on your side of the Cascades there is more alfalfa, while the west side has more grass hay. My area (Southern Oregon) is almost all grass hay. It might be worth the trouble to find a source of cheap grass hay on the western side of the state, then go in with some other folks to make a bulk purchase that can be delivered. Or, if you're closer to Idaho, I would think that there would be grass hay up in the panhandle, or in western Montana??? (Just guessing, based on my memories of those areas.)
Growing up in rural high schools we took ag classes and we had to learn about all the hay grasses. You might look for specific types: timothy grass, orchard grass, oats, rye, etc. I can't remember all the types, but there are many. A basic google search should get the names of the most common varieties. Perhaps that would make more sense when you are asking around, if you used the specific names.
Best o' luck!
Dan