== Clerks ? == 

 I think the 1994 film Clerks fits in the category as well - it's ultra-low budget (total approx $20,000), and had the director of production (Scott Mosier) playing several roles in the film. I won't go into the cheese factor of the humour, or the fact that the script very neatly hides the fact that the interior shots were mostly filmed at night (when the store was closed).