Lotta guys that do a fair amount of snaring make their own snares. There are several suppliers of snare cable, locks, and other parts, and with a few tools you can make your own. I'll show a few pics here of how I make fox snares. These are kill snares, and not for use as a restraining device.
This first pic shows the tools I use, cable cutters, a hammer, and long needle nose pliers. You can also see 3 strands of cable. For fox, I use 3/64th in., 1x19 cable. Start with a 30 in. piece of cable. Slide an aluminum stop on the end and pound it flat with the hammer. You can see my bench top vise which works as an anvil to pound on. Once the stop is pounded flat, (middle strand in the pic) take the needle nose and bend the flattened stop over 180 degrees (top strand in pic)