I looked at them after doing a search.
I'll bet the price makes it pretty prohibitive to buy for small production or just to plant flowers for bees.
Like mentioned before, I would not use then on un broken ground. I have a heavy 6' harrow with a 6' piece of railroad track on top for extra weight and I have dragged it with my 58 horse tractors and the first several passes it barely gets into the soil. I take a 2 blade, new ground plow to turn the soil and then after letting it sit for a month,to let roots die, use the harrow to break it up and level it out. Even then, on fields that had bushes, it takes several passes. After that, the harrow works well by its self.
Jim