You CAN still buy games at JoyGP. Why would Bada keep the site online if it wasn't working? Plus he said that he would make a clear announcement that everyone would know about when he is officially closing his doors. He has imported a bunch of official GP32 games from the Non-Exporting-Gamepark-Korea site for me (including copies of WBW, thank god!) and promised he would let me, as well as the GP32 community know when he is pulling the plug.
So as for Mill, download it from JoyGP ASAP! It is one of the best games on the GP32 (the others are ASR, WBW, and Blue Angelo). You will not regret getting the game from Bada, but you will regret not having it when JoyGP does close.
As for a demo, it doesn't exist.
There is a patch for the game on the GPspain site, but I have no idea what that does. Whenever i apply it, I see no difference.
GET MILL NOW!!!