The center consoles sell for about $350 new / used / locally / eBay. Regardless of where, $350 seems to be the going price.
I got mine on Marketplace for $100, and the seller drove over 100 miles to meet up. It was not out of his way, he just happened to be coming to my area on that day.
Best part: It was literally brand new. They took it out of a brand new Tahoe to install other items in its place. So now my K5 has that new car smell. For installation, I used two 12" 2x4 sections. One attached to the bottom rear of the console, and one installed on the truck floor where the front of the console sits. The wood fits the frame of the console perfectly, and gives the whole thing good support and stability against the floor of the rig. The 4 corners of the console had heavy duty metal brackets where it would be bolted to the Tahoe. I used very large screws that have 7/16th bolt heads on them to go through those metal loops into the floor (after drilling some holes).
I put all 4 screws in loosely, and then cranked them down equally. I'm really surprised how secure the center console is. Its solid.
Took about 30 minutes to install.