"What I would suggest is that parts stocks be attributed an approximate cost/value. Stripping donor bikes and subtracting selling prices is allowed provided the unused parts are actually sold, and no values associated may be less than zero. Otherwise estimate the real cost/value of the parts."
Just thinking out loud........ a Shimano 600 tricolor group including wheelset, dt shifters for zero from a too small Cannondale R800. Couple with a zero basis Teledyne Titan titanium frame or a Cannondale Black Lightning acquired in a trade from Henry III? So out of pocket would be bar tape, cables, housing.