The Tuber magnatum is the most valuable truffle because it has a distinctly alluring perfume and although its taste is delicate it fulfils the quintessential sensation we expect of a 'truffle'. Due to the high price it commands, secrecy abounds.
Find a truffle and it's like finding money buried in the ground. Depending on quality, white truffles the size of a walnut to a grapefruit sell for about $200 per ounce. The dealer has disappeared. Deals are consummated outside, around the corner, out of view. I did not see either truffle or euro change hands.