Multimedia R-Link2 = 500 euro
Air conditioning module = 100 euro
(acquired brand new from factory in France)
Installation is challenging. My friend is Renault certified "mechanic" and has all the wiring diagrams and configuration files necessary to do this.
Wiring diagrams are used in order to connect all the necessary wires based on model of Kadjar (trim level) you have. Then multimedia module needs to be unlocked which can be done only with official Renault diagnostic tool.
Next is configuration of settings and sync between digital dashboard and multimedia.
Last step is connecting air condition module in order to use buttons and "wheels".