Hey Leo!! Are you listening?? So what coins did you use on the Precision Bass? I know the Jazz didn't come with any but that's almost 10-years later...Early builders of electric basses used readily available coins as fret markers for the 3rd and 5th frets. They used linoleum dots for the others.
Hence the phrase "there's no money above the 5th fret".
True. It's all true.
That would almost explain the saying and would be really cool if that's the case, but what early bass makers did that and when?? I know there were a number of unsuccessful attempts at making and marketing a Bass guitar before Leo but no one had the success that Leo Fender did...to the point most people don't know that someone else invented a bass guitar before him. All that a Google search came up with was your statement here on TB...so, inquiring minds want to know!

Good one. I need to use that...soon. Maybe on a drummer.