Trinity-
To answer your question:
I found a notice posted by a retired English teacher at our library. He was offering help with SAT prep. I called him up and said "Hey...".
He LOVES working with my kids because they are interested in what he has to teach.
I found a math tutor through a friend - when I was introduced I said "Oh, you're a teacher??? Well, I've been looking for someone..."
I would encourage you just to approach the people you mention. Really, good teachers often miss teaching when they retire! If you think your son would be at all attentive, I'd go ahead and do it - you are offering to do the retired teacher a favor!
