The $438 price for the trolling valves are only if you purchase them when you purchase the gear. Actually the amount if you do this is now $650 and $750 for the mechanical and the electrically activated trolling valves.
If you purchase them separately (without getting a new transmission) then the prices are the ones in the attached quote. I don't quite understand Zf's theory about this pricing, but they will not budge on it.
As of now one of the mech. version is available with the second one about two weeks out. The electric trolling valves are about four weeks out.