In my experience with retreats they are usually sponsored by a guild. The guild often uses some of it's group treasury toward the expenses. They usually only open a slot up to an outsider if they need more people to meet their expenses. I would enquire at your local quilt shop about contact information for local guilds. The only way I have seen strangers at the couple of retreats I attended was if they were sponsored by a member of the guild. Each person attending a retreat usually has an obligation of some sort to the group like providing a snack or bringing some equipment to be shared during the event. A perfect stranger should be very uncomfortable. Like showing up at a wedding reception uninvited and gift less. Most retreat facilities also have shared sleeping facilities, not beds but bedrooms and baths.