I bought a pair of these at Harbor Freight ($4-5) and, when I realized I needed two pairs for two sawhorses, I bought a 2nd pair at Home Depot ($8). So I spent $13 or so on them, plus the 2x4's. Then they wobble, so I added cross-members to each one on the sides, front and rear. If I had it to do over I would have bought the complete ready-made versions.
HD version was much better. The Harbor Freight version was about
1/8-inch too narrow for standard 2x4's to slide in, and I had to take a pair of pliers and bend them open wider, so they ended up not fitting flush.Unless you need them to be at a different height or width than standard sawhorses, I would buy the regular ones.
One time I did make some from 2x4 and fastened with hinges, so that I could collapse them and store in a small space. For the braces I used a rope instead of wood and it worked fine.\\