I just bought one for the '91 yesterday on E-Bay From Cardiodoc. He seems to have them from time to time. I've seen his posts on caddyinfo.com before the price wasn't too bad $52 in pristene condition.
Call my buddy Ed... 219-931-1509 after 5:00 pm central time. He buys/sells manuals of all kinds, usually at swap meet. He's a good guy. I buy from him at swap meets everytime I buy a "new to me" car. Which is pretty often