RE: So what have you learned about foot plots?
I second the chicken litter, and its cheap (or free).
And let me add 1 thing-
look at where your weeds are the stongest and thickest, there is a reason for that. That soil has more nutrients than soil that is more baren. Plant that area and you'll likely need very little soil building.
And a second- you can make a very nice plot with hand tools and hardwork, you dont have to have implements, its just easier that way.