The default suggested price for premium UGC on the marketplace is set to 200 credits which is equivalent to $2 USD. But we expect it will vary depending on the content and the games.
Game publishers define price guidelines for their game, and ultimately, content creators are free to set up the price they feel is the right one for their premium content. There is no standard enforced by mod.io on what is the cost of a piece of premium UGC.