OK, first of all, that is probably close to a fair price if all the following are there: Paint is not peeling from anywhere...these machines sometimes got aluminum rot. The Bobbin case is there. It has some feet. It has the power cord and the foot pedal (2 pieces). No deep scratches or dings. The cabinet alone is probably worth the $60 you want to offer, as cabinets for 301s are very hard to find.
You can offer less to begin with...he may take it! But I would pay the $80 willingly!!