Convention is at the Spearfish Holiday in and Conv. center...$119 / night w/ "IMP" discount. A lot of the attendees stay there, but not all. Ph 1-605-642-4863.
Try the Kozy Motel near downtown. ph 1 - 605-642-4846. There are other motels and hotels too. There are about 2 or three hotels next to the conv. hotel. go to www.switchboard.com
I stay at the Spearfish Campground near downtown. It is nice and reasonable...about $20 / night for camping. I recommend it if you don't mind camping. It is easy to find. Go to main drag of downtown. Go 2 blocks west and then head south. You will run into the city park and fish hatchery. The campground it just past the hatchery. Easy.