There is a state park right on the edge of town:http://fwp.mt.gov/parks/visit/whitefishLake/
Haven't stayed there, but I have heard it's noisy due to a nearby rail yard.
but I hear it is noisy due to it's close proximity to the rail yard.
There is a KOA south of town on U.S. 93. Maybe about 3 miles gradually up hill, then you descend down into the campground. We started a tour there in '09. Relatively quiet for a KOA and lots of trees. At the end of the tour, we stayed at the Best Western on U.S. 93 south of town. I believe it's near the Super 8. Not cheap, but not super expensive. Then there is this place, which we saw but did not stay in:http://www.cheapsleepmotel.com/roomrates.html
Too bad the Bunk House Inn and Hostel didn't make it. Stayed there in '99 and '00. The owners were very nice. I think they still live in the house next door.
We used Glacier Cyclery in '09. Great group of people. We even rented a trailer from them. Make sure you make an appointment well ahead of time.