Hmm, that's a tricky question. I don't have anything against it from a game perspective if it is fully free to play. It's not really in the spirit of a game jam if those wanting to check your game out so they can vote on it have to pay money.
Alright, great!
To clarify, no money will be allowed to be inputted, all in-game monies will be earned via in game and only used in game.