I've been on many quilting retreats. The fee varies from $150 to over $500 depending on where you stay and the activities planned.
I'm going on one on Cape Cod in November. We are on our own for food. The $150 fee includes our hotel room for three nights and a small space in the common room. The $500 retreat covers all food in a very nice hotel for two nights and lots of space in the common room.
Some quilt shops put on retreats, so ask around at the quilt shops. Seems like your area would have lots of quilters. When I go to Lancaster with my parents, we get off in your town and head to Shady Maple for dinner. :)