Courtesy of John S., Blue Ribbon Eggs, Franklin NC
You mentioned that you're already gardening. If that's the case, apply SPIN principles to what you're already doing, and go sell some stuff. Earn some extra income, learn the business and marketing side and build.
SPIN Farming has the lowest capital investment cost of any legitimate business I am aware of that will gross $25K+ in the first season. In terms of net, that's up to you man, not the business model. If you follow the SPIN system you will do very well. If you're like some of my friends (dumpster divers and all round scroungers), you'll do extremely well.