Prices of various parts taken off of the web sites of Digikey and Futurlec (I've sampled all my semiconductors, so they haven't cost me anything) If you wanted to build my EEG system: ------------------------------------------------ Analog section -------------- INA114 $7.90 Futurlec AD8605 $1.68 Digikey MAX7401 $2.65 Digikey TL062 $0.25 Futurlec ------------------------------------------------ Digital section --------------- PIC12f675 $1.90 @Futurlec, $1.93 @Digikey 78L05 $0.20 Futurlec TLE2426 $1.30 Digikey PC817 $0.15 Futurlec (need 2) DSUBPCF9 $0.55 Futurlec 4xAA Battery Holder: $0.30 Futurlec ------------------------------------------------ various resistors and capacitors (price unknown) ------------------------------------------------ ================================================== Various parts that I have priced: Instrumentation Amps INA114 7.90 Futurlec, 8.40 Digikey (5.25/1000) INA128U 9.40 Digikey INA128UA 5.80 Digikey LT1168 3.70/1000 (Linear's listed price) AD8553 2.26/250, 1.64/3000 Digikey Op Amps TL062 0.25 Futurlec TLC277 1.78 Digikey OPA277U 2.03 Digikey AD8605 1.68 Digikey Filters MAX296 4.43 Digikey MAX7401 1.98 in 1k quantities, $2.65 Digikey Power supply / Voltage reference 78L05 0.20 Futurlec TL431 0.35 Futurlec TLE2426CLP 1.30 Digikey Digital stuff PIC12f675 1.90 Futurlec, 1.93 Digikey MAX232N 1.50 Futurlec, 0.90 Digikey MAX232DR .85 Futurlec Hardware 4xAA Battery Holder $0.30 Futurlec DSUBPCF9 $0.55 Futurlec