I’ve had a lot of luck at flea markets. Most of the saws that I’ve found there are probably from old miter boxes, but I’ve found several larger saws with nice heavy backs on them for three dollars or so. My advise is to get a couple of saws and then learn to sharpen them properly, even if they’re cheap saws. If you can turn something from crosscut to rip tooth or vise versa, then at least you can make a saw do what you want. Be content with removing a little rust, too. I’ve found lots of great tools under the rust. All I can say is that its fun, and it was a good way for me to get started. I’m far from a master, though.