If you are in the US then I would suggest you buy one from the sharper image. Then you will have a choice of either solving a riddle for a prize from Sharper Image, or take part in the Pyramid Hunt..
I think the riddles are supposed to be solved by the individual and not supposed to be shared?
And the free ISIS will most likely be hidden in larger cities so there is more of a chance of more people looking for it..
It's a great adventure so you won't be wasting your money if you buy one