Frankn, you just dont get it! Your "fair" offer is only fair for you, not the LO. Its not even fair to the members here. Havent you ever bought a car, antiques, used equipment? These things dont have a marked price, or at least a price carved in stone. One person throws out a number and the other counters with another number, if he isnt satisfied. Even big corporations are bought and sold that way, there are no numbers carved in stone. If at the end of Negotiations, either the deal is done or one of the parties walks away. They dont hang around and wait for the other to die! To sweeten a deal, other things are agreed upon, something else thrown in.
This isnt something we should have to tell you, you should already know by now, but you are stuck on this figure and will not budge. You will not get that cache without him, but its possible for him to get the cache without you!! He is the one with the cards, a full house and your only holding a pair and trying to bluff.
Since you have the facts, and the rest of us can just guess, my guess is that the cache could be found with any high end detector, since they are not usually buried that deep. Nine acres is not impossible to search, not even that hard, no matter what the terrain. He already knows there is something extremely valuable there, he is half way smart, (probably much smarter than you have given credit for), so nothing more to do than get his own detector or hire someone, at a much cheaper price than 8m! Do you get my drift? He has all the cards and even can choose the deck! All he needs to do is do a few searches on treasure and caches, and if he searches long enough, he will run into this forum, then he will have everything!
I think most of us here are fairly loyal to fellow hunters, and if someone finds his "honey hole", we might leave it for him, but now were talking about 12m and that is a whole different game. All the LO has to do is contact a few selected members here, and he could recover HIS treasure for almost nothing! Any one of us would be happy to help him find it, for the hunt, for the experience, and for money. If someone paid me 100k to hunt his 9 acres, I might be out there for a year, and if its there, I would find it.
Now on the other hand, if you wouldnt have talked down to us, we might have had more sympathy for your cause, but you spend time with silly jokes and your "cache hunter" attitude, so im sure there are members here that would even hunt that cache for FREE, just to pi$$ you off.
I just hope you realize that your pair of duces is not the strongest hand, make that terrible compromise and start digging! I dont like to talk about peoples age, since Im getting up there too, but hey man, at 74, you cant afford to play the waiting game too long, and even if you somehow succeed in that game, what will you do with the money, use it to buy a place in a rest home? Stop trying to make out like the LO is a worthless crook, explain to him (in person) and come to a deal you can both live with. But that compromise does not include 2/3 for you and your partner, live with it!