Borg equipment sells the valves. The chrome kit of four is about $110. Not cheap. Turns out my truck tire guy had an entire assortment of brass ones on hand.
Also the cost of the dismounting valve insert, mount and balance of six tires was $210. So if you are serious about monitoring your tire pressure and temp with a remote it's not cheap. I spent almost as much on the valves and mounting as I did on the TST monitor. For those on a budget, I'd suggest adding the longer valves just so you can add air (without having to remove the fave wheel covers) and use a cheap digital tire gauge manually.
One last note. While I was at the tire place getting this done, another Rv came in to have his tires rotated. The tire guy asked him, How long have you been driving on that inside rear FLAT tire? The Rv owner didn't even know he had the inner flat!