EDIT: I increased my bid so I am in the lead again. But it is more than I want to pay. I hope the other guy does not jack my price up too much. I need it for code testing...
I asked the vendor if he would sell me one directly, and he wants $200. He said the previous one went for $200.
I got my other one (now broken) for $100 (including shipping) and it was not a demo. It takes significant work to "undemo" the DX demo units, and there is not yet a simple method that I know of. Why the sudden demand for DEMO units? They MUST be using our methods documented here. Even the vendor of that DX demo says in his listing that they can be hacked for full functionality using instructions provided "online" (i.e. here).