Original mechanical drawings for rock crushers, gravel & screen conveyors, asphalt & concrete plants--Market value

I'm assisting in the closure of my friends estate---Mr. Delorme was a member of MENSA and the drawings are his lifes work--Also available are numerous photos of actual equipment and POP brochures---There are 17/18 bags/boxes of prints that have been discharged by the provincial executor---The purpose of the question is to establish a fair market value prior to posting the mechanical drawings for sale---These drawings can be seen in S/W Ontario---