With stock varying by ZIP code, Target retail stores offer the Munchkin Adventure Time Card Game, model no. MUS085, for $10.39. (The link is for reference only; you must complete this purchase in stores or spend $25 or more to avoid the $6.25 shipping fee.) Outside of the price below, that's the lowest price we could find by $7. It is both a standalone game and an expansion for other Munchkin card games, which are satirical games based on the clichés and oddities of Dungeons and Dragons and other role-playing games.
Of note, for Prime members only, Amazon offers it for the same price with free shipping, although stock is limited.