What I don't get, is where you chase someone down, convince them to ALLOW you onto THEIR property to hunt, and you are doing them a favor, and entitle to keep everything you want. Once you got them on the hook, you want to change the game, to onesies-twoies, or what ever 'fair way' to split finds. Then there are some, who suggest pocketing all the best stuff, and split the bottle caps and clad.
You asked, the property owner set the terms, why not just except them, or walk away? His land, his rules. If it were my land, I'd change my mind too. He never said he'd actually take anything at all, just reserving the right to pick through the spoils. He can probably afford to buy any coin, bright shiny, new, and clean, real collector value. The melt value, pocket change. Might be cool and interesting, but worth more to you, than the property owner. If he was really that tight and greedy, he tell you to take a walk, and hunt it himself. The stuff he wants, might not be because of the dollar value, but more of the historical nature.
An old, well used, virgin site, and you would over risk losing an operatunity to hunt it, over a few chunks of metal, that you would get anyway, if you never got to hunt there in the first place. No matter what you get to keep, under the owners terms, is going to be a whole lot more than what you had before hunting it in the first place. You still stand to keep much more, than you would find beating the same parks everyone else has been for years.
Now, there are some pretty rich guys out there, who are very tight with a dollar. When I bought my house, the owner of the crappy little apartments next door, was an older man, a retired doctor. Those apartments, use to be his office where he practiced. Old building, always needing repairs, which he, his sons, or somebody who owed a favor, would be doing the work, usually with reclaimed parts and materials. I help occasionally, when him or his wife were there alone, and struggling a little. Gave the doctor rides home, to hardware store, when his wife had their car. The man wasn't poor, he had at least 4 other rental properties, some serious acreage at his home, old farm, private air strip. Yeah, use to own his own plane, and fly. The doctor would pick up pennies off my floor board, or any loose change, slip it in his pocket...