The Collection is the working title for the follow up according to Marcus Dunstan and Patrick Melton! Personally I really liked The Collector and the creepy ass character and his torturous ways and habits.
Thanks to BloodyDisgusting here's the good we have for you today;
"a November start date has been locked for The Collection, Marcus Dunstan and Patrick Melton's collaborative sequel to their The Collector. Dunstan will return behind the camera to tell the story of Arkin, a man who survived the grasp of the first film's killer. He's teamed with a group of individuals who band together to save a woman captured by The Collector. Casting is currently under way."