There is a badly corroded mk-85 on one of the major auction sites that is basically selling for scrap. Last bid I saw was $20. It's a walnut stock. The wood badly needs refinished but the grain was fairly nice. I forget the site. Try auction arms, gunbroker and gunsamerica in that order. You have to search under
MK85
MK-85 and
MK 85
as each permutation will bring up different rifles.
Good luck.
John