The '85 will get you 15-25 depending on condition. The 70's will get you a bit more, 20-35 range depending on condition as well. I bought one for 35 + shipping on ebay, it did not look two days old and was in great condition, numbered with no signatures. I would be interested in the 1st 1970 listed if at a fair price. Hope this helps. Also you might want to contact the Arizona Wildlife Federation in Phx. They get older books donated back on occasion that they re-sell.
Andy in Tucson
520.490.0723