Springs are about $100 - Either Racetech, progressive or Wilbers. You can change your fork oil to a 3, 5 or 7 wt. Works almost as well as re-valving. You can call the manufacturers and tell them your weight, riding style etc.. and they should be able to recommend a spring and oil weight for you. I replaced my springs/oil with a floor jack and hand tools - took almost an hour. Easy mod.
Edit:
Do a search on the board for Wilbers - There is alot of good info on springs, oil wt, oil levels etc..