I don't think old monkey wrenches are worth much. They are soo common and easy to find. Maybe there are specific ones that are worth something. They are cool to collect. There are many variations.
I think the highest dollar one you have there is the Ford wrench. I have seen them go at flea markets for $20 and up when in good shape.
Coach
What are they called, Stilson or something like that?
They look OLD and neat, so I've bought a couple at yard sales for $2 or so. Not rare, but its nice to have some tools that have stood the test of time.