Run time cost effectiveness

How long (minimum runtime) must a movie be to make you feel that it fulfilled the cost of a ticket?

I passed on a movie that only had a 60 minute runtime and Drive-Away Dolls (84 minutes) are on the outside edge of it being worth buying (even with A List) a ticket to go see.

My minimum runtime is 90-95 minutes, with exceptions of a film being on the close to 90 (85 minutes the outer limits) minute long runtime.