A truly great cover for Detective 365 (July 1967), and an amazingly awful story, by John Broome, Sheldon Moldoff and Joe Giella.
The Joker starts selling his merchandise at cheaper prices than Batman. Yes, that is what the story is about. The Joker even commits the dastardly deed of opening his own department store.
Batman and Robin will have none of this! So, everybody fights.
The Joker house from the cover is one of the items for sale at the department store, and serves as the setting for the final fight scene, but it does not look nearly as cool as the cover image. A let down.