Have you considered just posting an ad on Craigslist to find someone to:

Take a walk with once a week
Go out for coffee on a weekend
Try a new activity once a month

Or perhaps have you tried volunteering a couple hours a week for a cause you like?

When I posted on Craigslist, I just said a bit about myself, including that I have PTSD and wanted friends I could be real with.

I got great responses. Very simple, free, cheap, easy, no commitment, and no one expecting me to be perfect.

Another free, easy, no committment option with a lot more structure are the free Anonymous meetings. They used to just be for Alcoholics, but there are many now, including Emotions anonymous and others that might suit you. You're not obligated to speak or do anything in particular except show respect when others speak.