Selling a cab is tricky. It requires finding someone who wants a cab and happens to have the same tractor as you. 1/2 the cost is a good place to start, however the way its advertised is important also. Find out what are all the models its listed for, determine how much it is to ship on a pallet. I would suggest listing it on craigslist, but also tractorhouse, fastline, and e-bay. If you want to move it quickly list it for significantly less. One of the reasons it costs so much to buy a cab new is because cabs fit so few models that they all have to be pretty custom.