Set price - government supported agency and a charity who are not out to make a profit but improve the standard of driving on U.K. roads - they run courses for fleets, bikers, lorry drivers etc and packages have been given away free by manufacturers as diverse as Daewoo and Honda.
The "Skill for Life" package is £85, includes you first years membership when you pass, local organisation membership, free observed lessons from your local organisation, a "How to pass your Advanced Driving Test" book (usually about £15) - it really is priced at £zero in terms of what you get. You basically pay for your membership, test fee, the book, and some admin costs.
SO worth it.
Brian.