About ~$700 for the GPS and ~$100 for the OEM mount and worth every penny.
Installation is literally and figuratively a snap and some screw-driving. The most difficult part was fishing out the GPS connector zip-tied to the frame, on the throttle side, under the metal fuel tank cover. To reach in and grab the connector, I had to remove the plastic fuel cover on the front of the tank. Even then it was more feel than see. On your 2012, however, the connector
isn't as buried -- cinch city.
Check out the Max BMW parts fiche for details and the BMW Motorcycles of Countryside "PROMO15" coupon code -- 15 percent off total orders and (I think) free shipping. I used to buy a lot of OEM farkle from Chicago BMW, with its 20 percent discount, but I'm fairly sure they went out of business. Countryside might be selling the same inventory under new ownership. Have not bought anything from them.
It's a terrific kit for getting around backcountry roads while getting zen with Radiohead. With its Bluetooth *stereo* audio streaming that is paired to a Jabra BT3030 receiver that is plugged into noise-isolating Etymotic ER-6 earbuds, the Navi IV is my favorite R12R farkle. I almost never motor without it.