Older kitties can be found on markets as well especially at the "love shacks" on the variety of markets out there.
At "love shacks" you find kitties (almost) ready to make a kitten and frequently older kitties can be found there which almost reached their retired age.
In the KittyCatS Addicts group you find a notecard of all secondairy markets I personally like the love shack @
Simply Too Adorable as they have so many seperatated in a shack for the girls and the boys.