Only the 54t and 36t ratchet retails for 170~190 from canadian distributor. Not sure why there's huge markup for those latter two ratchet upgrades.
Jenson says $94US for ratchet, springs [HTML_REMOVED] grease (a little cheaper just for ratchet):
http://www.jensonusa.com/Freehub-Bodies/DT-Swiss-36T-Star-Ratchet-Upgrade-Kit