I was one of those who bought "Masquerade" way back when, not because I thought I had a serious chance of finding the treasure when lots of die-hards were spending lots of time on it, but just for the fun of finding all the hidden things in the book, and wondering if they actually had meaning or were just coincidental patterns. Anyway, I didn't win, of course.
The cost of the treasure for that one was covered by book sales, which would be difficult in the modern era, so unless some eccentric rich person is wanting to have some fun, I don't think we're going to have any expensive treasures. I think the closest thing we're going to get to now would be some sort of promotional puzzle, where a company promoting a game would come up with some online adventure that leads to something amusing.
Telltale did something like that with the time cards in the Sam & Max Season 2 case files. You only got one time card per case file, so it required some cooperation with other players with case files to track down what you needed for the secret "treasure."