In August & September, you can fly from Austin to Kalispell, MT for under $500 roundtrip since it's considered out of season. It's a quick 6 hour flight with a stop in Denver on United.
There's a ton of really good trails around. In particular, the Whitefish Bike Retreat is pretty awesome. You can camp and ride some short but really fun flowing trails on the property. It also connects to the Whitefish Trail which has 20+ miles of single track. There's 25 miles of downhill at Whitefish Bike Park on Big Mountain.
I think it's really good riding for place not many Austinites would think of going since at first glance it appears difficult to get to.
