Or make your own. These are 2 fret saws that I made a few years ago. I also made a jewelers saw, but cannot find the picture of it. On the jewelers saw I used a 5/16 bolt for the end clamp assembly pieces with a small piece of flat steel that was threaded for a machine screw. I first hacksawed the for a flat spot and then filed it smooth, drilled ad tapped it so the flat piece I added would get a good clamp on the blades.
With the threads on the steel rod at the top I get better control of the tension on the blade. Still trying to figure out a tension system like the Knew concept saw uses, but it has a low priority at this time.
Here are my 2 fret saw. Both use pinned end coping saw blades, the blade holders were made using a 1/4 bolt with the head cut off. I cut the angle slot with a hacksaw, the same with the center cut. The stretcher bar has a tenon on both end and that fit in to slots.