You are probably barking up the wrong tree here on Pprune regarding your manual requirements. Part 121 and various AC's will outline the manual requirements for a 121 operation. You may find some third party companies will produce a 'template' set of manuals that you can adopt however there will always be huge volumes that you will have to produce yourself. Jeppesen may be a useful place to start.
Typically your operation will need a GOM (General Operations Manual) which may be broken down into as many as 13-14 seperate manuals. ie Mx Manual, Emergency Response Manual, Flight Operations Manual, Flight Control Manual (dispatchers manual), Inflight Service Manual (Flight attendants), Flight Standards Manual (Aircraft specific procedures for pilots) Training Manual, HAZMAT etc etc.....
A very good place to start would be here
http://www.faa.gov/library/manuals/e...a/2_061_00.pdf
As for buying these already, I could not say where to start, only that either way, you have mountains of work ahead of you.
The FAA recommends using a Certification Consultant in obtaining Part 121 certification. See here http://www.faa.gov/safety/programs_initiatives/oversight/atos/air_carrier/data_collection/media/applicant.pdf[/URL]
In the same document they indicate that Inadequate manuals is usually the primary reason that operators fail to meet Part 121 requirements during certification.
Good luck
MJB