Don't touch them with a 100 foot barge pole!
They want you to pay them for the priviledge of making money off your game. This is the same scam that the writing community faces from time to time. Money is supposed to flow to the author, not the other way around.
Of course, this doesn't mean that you don't fund your own development, or marketing if you are going alone. But you sure don't pay a publisher to sell your game!