If you don't mind me sayin', this "want to buy" might get more responses in the "Shooting Accessories" forum rather than here in the "Firearms" forum.....
It's always good to be set up to cast round balls. But I'll point out for the sake of convenience that Hornady sells .350 sprueless round balls (in addition to other sizes of buck shot) in five-pound boxes. I bought a box about two years ago for under $30. It has been a real time-saver.