Saw jointers are quite common and not used by many today. Not many people use hand saws anymore and if they do, they have no clue on how to sharpen one or even take the time to do it. I have a few different ones and some different saw sets also. Most sell in the $5-$10 range unless it is an odd patent that someone wants. I have bought jointers at garage sales for less than $1. If you buy from a retail tool collecting site, prices are much higher. I do not know how many they sell though.
The best buy I made on a hand saw was at an estate sale during my lunch hour years ago. I bought a Civil War era Disston for $5. That is the oldest saw I have. I have some saws that are totally unuseable because they have been jointed and sharpened so many times, only about half of the blade is left.