So you can't pay people to vote for a particular candidate.
If they want to sell their vote - it is their choice. I'd only say that the right of citizens to secede from such a society must be respected too.
That's illegal, and (somewhat contradictorily) not non-repudiable. You can take a picture of yourself with "ballot marked for candidate I'm paid/coerced to vote for" and then step right out and say "oops, I messed up my ballot, give me another one" and then submit that.
Also, California allows for absentee voting with no particular reason. I've voted in every election I've ever been eligible to vote in and I have never once set foot in a physical polling place.