There was a bit on Daily Planet (It mighta even been back when it was still called @Discovery) a few years ago, about a rig that could be built into an accoustic or electric guitar, under the saddle, that would read the sound from a given string, and automatically compensate for what note it was playing, (real time, automatic intonation and tuning adjustment... )

I seem to recall they pegged it somewhere in the $10,000 range... plus the price of the guitar...