This is my third guide about getting stuff (legally!!!) for free that some users on ebay are charging money for.
Playstation 3 game save files are easily available for free to download of the internet. I have seen these for selling from 99p to a few pounds. Most of these probably came from the same sources I will share if you here.
Due to ebay rules, I cannot give you direct links however search 'ps3 game saves' on google and you should find plenty of sites! Send me a message if you are not sure and I'll pass you a link to the site I use.
Most of these sites should give instructions on how to install, however here is a brief guide: