I've been to Pinewoods for Folk Music Week three times, The Swannaowa Gathering once for Contemporary Folk Week, and Augusta Heritage once for the Stringed Emsemble Workshop (During Irish Music Week). All were great experiences, well worth the expense and time.
If you consider that you are paying roughly $100/day for room, board, and first-rate instruction, coupled with the opportunity to meet many others who share your love of music, the price is quite reasonable. In my case I had to add the cost of travel and lodging to and from the camp, but it still was a bargain.