Balancing expected payouts for a lottery ticket in a video game

I'm making a RPG-style computer game, and one of the items the player can buy in-game is a scratch-off lottery ticket. I'd like some help in calculating expected payouts and how to balance them so that the item is nice but not too useful.

The model I'm currently using: the ticket has 12 scratchable areas. Each contains one marker with the following probabilities:

0.5 nothing, 0.1125 small win, 0.1125 medium win, 0.1125 big win, 0.1125 surprise, 0.05 jackpot.

Every three of the same type of marker results in a win of that type, with the following payouts:

small: 5 times ticket price

medium: 10 times ticket price

big: 25 times ticket price

jackpot: 100 times ticket price

surprise: a random gift item of no (direct) monetary value, but possibly useful in other parts of the game.

I want the expected payout to be slightly below ticket price (so the player can't cheese the game just by buying a ton of tickets) but the chance of winning to be high enough that the tickets stay fun to use.