Looks like a nice piece, gold cap I'm guessing, box looks in good shape too. There are some fans of C-Case Seamasters and Constellations on here that will have the info.
It's a 166.0130 with a caliber 1012 inside. The sister watch is the 166.0131 with the 1022 day/date. Not a bad watch at all, but not as desired as the earlier Cosmics with the 565 date or 752 day/date movements which is probably why you got it inexpensively. Pretty nice watch in great shape. 👍