List is ca. $184 and you can find the kit for ca. $130 plus shipping. Keep in mind that if you go this route that the ECU will need to be flashed to accomidate the 5v glow plugs and that will run $50 for an update to the GDE tune if you have one or $100+ at a dealer. NOTE if you drive to a dealer to have the flash done be sure to do so either before you install the 5v plugs or with them disconnected.
Alternatively for about the same $s out of pocket you can get the Etecno1 7v glow plugs (
http://www.dieselglowplug.com/) that drop in with no ECU flash.
I've seen/heard mixed results from both at least in really cold areas for starts without use of the block heater. In warmer areas, like mine, and with the block heater they both seem to do ok.