Here's what I used: two 16" disc hillers mounted behind the rear tires at 45 degree opposed angles. Pulled them with my 18.5 hp JD 4010. Made nice raised rows.
Got the disc hillers for $30 each at Agri Supply. A friend of mine made some clamps to mount them onto my old JD M soil ripper 2x2 diamond bar (that my friend also gave me).
Think you can get soil rippers, or cultivators with chisel plows, from buctraco or other folks (probably Agri Supply). Most of these are made to go on square-mounted 2x2 bars. You can get clamps from them to mount the disc hillers. I had to get my own clamps made because the old JD M soil ripper bars are mounted in diamond pattern, not flat.
Since then, I've bought a couple 12" discs and mounted these onto the disc hiller shanks. Then I've mounted 4 chisel plows for ripping the rows this fall/winter. The smaller discs will sweep between the rows and still allow the chisel plows to drop into the row dirt to do their work.
Ralph