Edit: As a sort of side note I've also been thinking about making a T-shirt that says something like "This t-shirt is worth 10 bitcoins" with a private key QR code on the back, and then see how long it takes for the account to get emptied.
Several players could be involved in this. The sponsor who offers the prize, two planters who plant the geocoins (could even be continents apart), and the two finders of the GeoCoins. That's at least 5 people involved. This shit (no pun intended, for I'm on the throne while penning this post) has legs.
~Bruno~
.... >_>
So, have a master lock on an account that requires multiple caches to unlock the price inside? Seems like it could go for years without being claimed, kind of like Ready Player One or something. Locked in a QR Code might be interesting though, would you just have it lead to an instawallet?
I'd hope it wouldn't be made that difficult to find. Even the harder geocaches I've seen have somebody checking into them every month or so.