I got one like this at Woodcraft of all places. It's okay, but
obviously a cheapie. Rockler has some that are black in color and quite
a bit beefier, meaning they lock into the miter slot much more solidly.
It was probably more like $12 or $13 but I'm happy with it. If I felt I
needed several more or many different kinds at this stage of my
woodworking, I'd probably learn to make them.

Tom