It wasn't a Pink Floyd member.

No. The saxophone solo on “Money” was played by Dick Parry, a session musician.

He was hired by the band for The Dark Side of the Moon and also played on other tracks. Roy Babbington and John Alldis also contributed, but Parry is the guy on that iconic solo.

It’s a common mistake to assume it’s one of the members. Floyd worked with outside players when they needed specific instrumentalists they didn’t have. So, not Roger Waters or David Gilmour—just a guy who showed up, played, and left.