http://en.wikipedia.org/wiki/General_Instrument_AY-3-8910
I found it in an old pile of chips so I don't know if it works or how much its worth,
Its not being produced anymore, so it might have some value.
Best to ask on a forum like the cpcwiki, who might know more. I doubt it is worth much though, but maybe someone is making a dual-AY solution for their own 8-bit computer.
