Here is another link, I read off Hack a day a while ago: http://emerythacks.blogspot.com/2013/04/connecting-ipad-retina-lcd-to-pc.html

I also bought a few old motorola lapdocks, and one of them I gutted to just a controller and panel. Its only 1366x768, but it accepts HDMI input, and is a good conversation starter at my desk at work when I use it for the occasional 3rd monitor. Other than stuff like that, there is not much that is higher resolution you can just buy.

I have been facing the same problem, and have just accepted the fact I either will have to buy the "smallest" retail display that has at least 1080p (like a 19 or 20"), or custom make something. I have been looking at using an ipad 3/4 LCD connected to a small board and using the displayport on my Macbook air.

I bought a panel off ebay for around $60 USD and am looking at a either a pre-made board at http://dp2retina.rozsnyo.com/ or seeing if someone makes a board for less money. The ipad 3/4 display is eDP so the boards are pretty simple. Then its just making a case for it, which is the hardest part for me!

This is really offtopic, but I used to work in a bakery with a bagel oven in it. It had 5 slabs of heavy ceramic plates that spun around slowly like a ferris wheel. On the door that you shoved stuff through, was a warning sticker with a stick figure crawling into the machine, and its upper torso was being moved by the plates while his lower part of the body stayed nice and neat in the door. Never before have I seen such a graphic warning. What is sad is that someone probably got cut in half once for that sticker to exist.