I would try ebay, This guy is selling just the mobo for $24 bucks buy it now. I would sell one of mine I have 3 spare and I would charge at least $30 for it. Your best bet is buy that board then buy the games when you find them.
I recommend doing as much research as you can on Hyper 64 Hardware and look up in the Hyper 64 section for details or any problems. I ran into a sound problem, my board came with two extra cables one was for speakers and the other for extra voltage (I think its to the built in sound amplifier on the mobo but im not sure). I had to cut off the molex connector and strip the wires bare and I got some small bare wire speakers and I had sound. The annoucer sounds very low but I think if I buy a external Amplifier it will fix it.