I bought s few cheap blocks over a few years, but I’d say make your own ! Basically start with a rectangle of ply, sick 2 lengths of baton to it ensuring they are parallel. Then Mark out a line to cut with a set square.
Then cut very carefully with a quality saw. The one above is an erwin pull saw.it was about 12 pounds I think.
I use this setup for Dowell etc, when I can’t be bothered to venture to my table saw in the cellar..