Marc, While there is money to be made from the surplus of a given venture, permaculture is not a trade based economy, it is a subsistence based economy. Therefore, it is not a "growth" venture that would yield a ROI satisfactory to meet typical investment requirements. The beauty of permaculture is that it's inputs are limited, it's outputs are the input to another system, therefore there is no waste (AKA polution), and it is sustainable with little human intervention once it is established. I personally feel the best permaculture investment one can make is in their own system so that they can move away from a trade based economy. The more one can produce for themselves, the less time they have to sell for cash to provide for their needs. My retirement goals are not only off the grid, but also off the economy living.