i think there is a company called core sound that specializes in binaural recording components, but i think they are generally geared towards live show/bootleg recording. probably worth checking out though, i remember the website having lots of info on binaural theory.
Core Sound
a while ago i wanted to get a pair of these to do field recordings for things like trains (i was in a "klf:chill out" state of mind), but i couldn't afford a good set plus dat so i didn't. but i might now, this thread has awakened something sleeping...