Manuals for year models prior to around '75 or so, (don't hold me to an exact date) are available for free on the Cessna Pilot's Association web site, (membership required) and for a nominal fee from a number of sources on CD-ROM. After a certain year in the mid-late '70s or so, Cessna retained the copyright, and you have to pay much bigger bucks to order from them. Your best bet for a deal is to watch ebay for them. I got both paper and electronic versions of both there.