Plain and simple like the old days.
There will be a number of chests each containing a different and maybe random amount of rupees.
There would be 3 difficulties each with varying chest amounts, which increase your chances of winning big while decreasing your odds. They all have a different cost to play.
Easy
Cost to play- 15 Rupees
# Of chests- 3
Prizes- 2 chests have between 5 and 20 rupees. One chest always has between 30 & 50.
Medium
Cost to play- 20 Rupees
# of chests- 5
Prizes- 2 chests always have 10-20 rupees, 2 chests have 25, one chest has 50-100 rupees.
Hard
Cost to Play- 50 Rupees
# of chests- 7
Prizes- 3 chests always have 30- 40 rupees. 2 Chests have 50, 1 chest has 100, and 1 chest has a Heart Piece. (After the heart piece this chest contains 50-200 rupees.
This could easily be modified to have any number of items if heart pieces aren't your fancy. It could also be modified for well, different costs, or there could even be multiple versions.
It's set up so that you have the same chance of breaking even as you do of losing a profit. You also have that smaller chance of getting slightly more than you paid to play, and a really slim chance to win more than double your pay.