My sister did a one day taster in the peak which cost about £90 but didn't really get off the ground.
I agree that to get a real taste you need to go on a 4 or 5 day course. I went on one in Bir Tibetan colony, Himachal Pradesh (Northern India) which cost about £30.
Accomodation and food was really cheap, so with air fare it probably works out about the same cost and you get to see some beautiful huge mountains!
http://www.webindia123.com/tourism/advent/gliding/billing.htm
The company I learnt with were called Adventure Dream Makers.
