I have been contemplating these for some time. Problem is they are one full yard of cured concrete and will weigh about 3-4000 lbs each. Shipping is a problem. Moving those on rough terrain limits the type of equipment you can use. The equipment that can handle them is fairly expensive. That is why I staked up some railroad ties for now. I am working on ideas for some other type of more permament bin that I can construct without hiring heavy equipment. More money in materials but less in rental or contracted labor.
I am thinking 6x6 pt posts with 2x lumber for walls like this photo.