What is being sold ,how and why? No one lost a great treasure without contingencies and back up's to their back up's , or did they?
I-you-we would not lose one would we? Not easily. Though we could direct annoying attention to a property owners land by hinting. Or simply sell something to scratch up some coin. Or attempt a flushing out of a possible prior activity shadowed by a lack of info. or have a cover story

A convoluted con could cover all of the above.
First though an audience with a few coins is needed.
Note "ears" , they will come up repeatedly.
Treasure. Ears perk up, and you have a select audiences attention.
Now the sales tactic may very greatly.. you can provide a service in exchange , or run all the way to a full blown con.
Not ethical but a coarse approach is to first confuse your audience. The Beale papers do achieve that as apparently no one new it was there but the veil of ignorance is lifted and here it is in full account.(!)
Promoting a local lost treasure with new info to be released creates a dependency on you for more info..and ignites competition more than free shoelaces even, depending on the pitch..this one including newspaper adds to boot.
Next create a dependency. Already done.. Easy enough by being the exclusive source of further information to the confused.
Now make the sale. "Here's your copy".
A shell game comes to mind with the ciphers ,the story, and recent history of the writings time in it's accuracy inaccuracies and rumor.
Follow one or all and are we guessing or knowing which is which , separate or all together?
That name rings a bell says this pair of ears,that site sounds, no wait I know where that is says another ,ya I herd something about that event back when chimes in another pair.....
Whether some one buys into or is sold or by contact comes across the Beale papers and reads them....
For many of them afterwards , (after Wards) the name Beale will from then on will make their ears perk up and they will want more information.
Some one or a party missed out on sequels to sequels in the saga by/for the original party.....but not everyone did since , sort of; still.
Beale. Just a name ...but it pops up now and then and makes previously un itchy heads itch.
Don't chase it when your ears or eyes perk up or you'll just chase it more. And there is always more.
(Ignore the urge to click the link.)
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=beale epa