You can go fishing for one single fish,kill it and bury it under your plant...they love dead fish, also seaweed is free and that helps alot. $5 can buy you a fairly big bag of sheep manure which really helped my outdoor grow. You can also use organic bottled ferts(no need for chemicals), make sure it has highest P (Prospherous) and less N (Nitrogen)
(N-P-K rating on bottle). Burnt banana skins are good for flowering as they have phospherous and also burnt Cucumber skins, blood and bone also (set you bck another $5 or so for a small bag)

I highly recomend fish though. One of our goldfish died when we transplanted them into a bigger pond so i burried it under close to my plant and it absolutely loved it, it thrived like hell once the fish decaded(i guess) and its free if you have a fishing rod or a net! Seweed also is best (alot of fertilisers use seaweed extract in their products)