One of the most popular things to do for conferences is to rent houses together. This might or might not be cheaper, but it’s generally more fun and a nicer experience. It also adds an additional workspace for the retreat.
Make sure you add yourself to the newsgroup for the conference, so you can make arrangements with other attendees to rent houses. Usually one person finds the house, and then others come and fill it up. Here’s a start if you’re looking for a house.
There are many AirBnB locations available; again, try for Crested Butte, not Mount Crested Butte.
Crested Butte has a number of hotels, varying from OK to nice, none of which are chains. Make sure you check the (albeit outdated in some places) details about lodging and how to get to Crested Butte.
If you’re in a hurry you can just call the Crested Butte Chamber of Commerce at (800) 545-4505 and they will help you make a reservation. Remember to ask for a reservation in the town of Crested Butte, and not on the mountain, in order to be close to the conference location. However, in the Summer there are always more rooms available on the mountain than in town, and the bus runs every 15 minutes between the mountain and town.
If you’re on a budget, try the hostel or ask the Chamber of Commerce about camping.
Here’s another site about travel, lodging and the Crested Butte experience.