I just planted a bank full of fruit tree's a couple of minutes from my place. The north facing bank was covered with wandering dew and nastirtums which I cleared 1.5m square holes in to plant a range of tree's which I've grown. The soil is of a moderate quality with plenty of insect life and humus at the surface but has a high clay content as well as a lot of general rubble mixed through it. The bank is north facing and fairly well sheltered so I'm hopeful that the tree's will grow and fruit well.
As the tree's were grown in my hot house the only real cost to me is the few hours it took to raise and plant them out, if only a few of them fruit it will still be a significant return on investment.
I planted two avacado tree's three tamirillo's and two mountain paw paws. There is still room for at least ten more fruit tree's in this space and plenty of other locations around the nieghbourhood to plant.