To make this homemade broadfork, I bought two sets of coil-spring harrow tine replacements at the AG-West Supply and drilled two tight holes in a 1-inch-square hollow metal bar, 26 inches long, for the tines to be driven through. Next, I welded hollow pipe — smashed at one end to get a stronger weld — to each end of the square bar. If I were loosening unworked ground, I think I would weld the spring teeth to the square bar, but for working raised beds, the teeth tend to stay in place.
I found two nearly new, long tool handles at a garage sale. I put a small bolt through the neck of each handle and the hollow bar to secure the handles.
I paid $16 for welding, $10 for the garage-sale handles and $15 for the spring tines. The hollow bar was scavenged, 3 feet of the square pipe cost me $6, and the bolts were $1.78, for a total cost of $48.78.