I think the problem is that even with high intensity LED lights, you can't come anywhere near to the point light source capabilities which a UHP lamp delivers. This means that they can't use a single reflector in a nice case like they do with traditional lamp systems, unless they go down to the Pico projector sized stuff, which is (notably) very reasonably priced.
The larger/brighter models can't accomplish LED lamps by using one bright LED, but need to use an array of LEDs, which then require newly designed optics to get the light tunnelled properly to the DLP chip. They are using the colored LEDs, which is nice and gets rid of the color wheel, but I am not sure if they are using a flat array of lights intermixed (RGB) or three separate light arrays of RGB.
With LCD, I would expect three separate arrays of LEDs, but DLP probably uses one. The redirecting of the light path with the larger light source would be something of a hindrance and has been something manufacturers have been dealing with.
As for why THIS projector would be more expensive is because of the manufacturer themselves. $20K, without lens, is pretty normal from these guys. I will try to get one to borrow from them for a few days if I can. Not sure they'll give it up, but I will do my best.