Probably a Venus 188, Landeron 148, or some sort of Valjoux 77xx caliber. Can't tell you how much it should go for, but it won't be as much as you probably think. Box & papers is certainly a plus.
I still have this watch, wore it a few days back. Does not get much wrist time. I have never opened it, and 2.5 years later I cannot recall why I stated it was a 7733. Welcome to the forum, and nice watch