I can do you one better, because we have exact cost calculated. Altogether the project cost $620. That's for all the metal involved in the plow frame, coulter mounts, and 18" coulters with hub assemblies. I am familiar with the open source ecology one, and personally I think they missed a lot of key design elements. They were very brave in trying to create a shank, but there is a lot of engineering that has gone into them and I don't think they can be replicated easily and still be effective. That is why we bought our 26" shanks from Yeomans. As for the frame, it looks okay, but it is being pulled on the front of the tractor. Even with their tractor design, an implement like this is very hard on the hydraulics that are used to control the front end loader. That is why the plows are mounted on the rear, this is the ideal spot to tow an implement like this. Each shank has a shear pin that breaks away at 7000 lbs, so on our plow three teeth equals 21000 lbs of pull. That's enough to make some serious and costly mistakes, if you ask me. P.S. I am in Western Oregon if you are ever over this way. I am about an hour south of Eugene.