I had the same issue with my wifes car (a GM product) when I wanted the Homelink unit that is built into the overhead lighting console, very similar to the one in the GC. Also, note that like the GC, there are multiple overhad light consoles - some with sunroof buttons and the one without (3 different models for the GC - no sunroof, standard sunroof, pano sunroof). With my wifes car, the headliner came from the factory in two different colors. This is not a issue with the GC, all are the same.
So, after checking with the dealer for new parts (very $$$) and watching eBay for almost a year - I started searching the local and online recycle parts yards. It took me nearly 2 months, but I found the console (without sunroof buttons, in grey) from a recycle parts dealer many states away. Final cost was $35 including shipping. It literally plugged in. Important - I made sure the dealer I bought from sent me the end of the wiring harness it was attached to. The Homelink had a unique connector. Otherwise, they are pretty much plug and play (ie: may have to find a power lead to splice into).
So my recommendation is to start e-mailing and phoning around. Many recycle parts dealers do not like fooling around with these relative inexpensive parts - too much labor $ to properly remove and some do not want to cut wiring harnesses or separate certain parts (ie: some believe the overhead console should remain with the headliner). I ended up buying from a small recycle dealer that was very helpful and willing to work with me. I found the dealer by watching for various interior parts on eBay for my wifes car. Many dealers post photos of the vehicles the parts come from, with a note indicating if you want anything not pictured to call - which is what I did after seeing the Homelink console in one of the photos posted.
Sort of like this one on eBay currently (I believe the color description is incorrect, all GC's are the same - sort of a light grey color). This one has the standard sunroof controls (the pano shade buttons would go on the right side). I would proceed with caution on this, as it does not appear to come with the wiring harness, but you could contact the seller to see if they can send it along with. The Homelink unit itself is self-contained in the console (ie: the sending unit is all there behind the buttons):
Grand Cherokee Over Head Roof Console Overhead 2012 Homelink Jeep 12 Tan Sunroof | eBay