I owned an affiliate site for elderly once and I can tell you it was one of the, if not the hardest market I've been in.
As people mentioned here before, flyering in places that those people come to works out (not the best, it's a start).
You must know, those elderly mostly live in special homes, and guess what?! They give computer/internet lessons in almost all of those homes. Try to get in touch with the owner and set up a nice landing page with links related to their course.
So in short, your site will be set as the starting page of the browsers in the elderly homes and will serve as a 'panel' with usefull links, also make sure you become in touch with the course-givers so you can add course-related links to the page.
Now this works like a charm and you get decent clicks (of course you implement your aff. links on the starting page). BUT...
Those old people, have a VERY hard time checking out it seems. They have 99% for sure no paypal, and will not set it up for buying one thing, so get that out of your mind.
The only thing I was eventually able to make money with is sitting down with companies who sell hearing-machines and alarmsystems to advertise. I have tried to expand this idea in more areas but the income is still very little compared to the energy it needs. There are better markets to be hit with this technique, like for instance handicapped (young) people who might actually enjoy buying things online and don't mind making a paypal account for example.