How about a sweepstakes on when (or if) rhodium will overtake Bitcoin. Of course with the rhodium bid/ak spread so high you would have to define which price is to be considered, probably bid since this is what you get when you sell. Rh bid = $7300 vs BTC around $7900.

1 oz of rhodium or 1 Bitcoin to the winner?!?!?!

Or if we are cheapskates, maybe a 1 ounce silver round.