I have several isolation amplifier boards that are the ideal interface
for EEG and ECG.  Isolation is essential for safety when connecting
line-powered equipment to electrodes on the body.  These boards
incorporate the Burr-Brown 3656 isolation module that currently sells
for $133, plus other op amps to produce an overall voltage gain of
350-400.  They are like new and guaranteed good.  $20 postpaid,
schematic included.  Please email me for more data.