I remember selling candy when I was a kid in school. We had a ban on anything that was called unhealthy too, but specifically gum. I would buy gum balls like the kind you would pay 25 cents for in a candy machine from a grocery store at bulk prices. I made about 20 cents a ball from them. I usually kept a tub full of gum, sugar sticks, cinnamon candy (really popular where I was), and licorice. I could usually charge about what they would charge in a convenience store and make healthy profit. I never did much accounting back then but I made about a thousand bucks and I had candy to last me all the time. I remember vividly the time a teacher caught me doing it, she made me throw all my stuff out. After school though, I went into the garbage and fished out all the stuff that was still sealed in wrappers and resold it. All she taught me was to be more careful and out of the open when selling things. Its amazing how much I learned doing the candy trade about profit margins, supply and demand, inventory management, customer service, and just general business from that. I also remember moving onto harder things after the trouble selling candy with the rules with slim profit margins brought that enterprise to an end. By the time I was done with school, I was the guy people would talk to to get anything at a fair price. I could get concert tickets, credit cards, custom cds, homework, energy drinks whatever. I can honestly say that I learned more about life buying and selling, taking profits and reinvesting it and absorbing losses in grade six than I did from any of my class work.
Well, as always, it depends on your definition of being cost effective. To get a nice cheap Skystream Windmill would be about $15,000 taxes in. This would produce enough power to comfortably provide electricity for a house or a small business (around here around 500kw a month). With proper battery and storage, one could go completely off the grid saving about 100 bucks a month. Doing that, it would take just over 15 years to get ones money back, but you can find that good will comes putting up wind towers, price of electricity doesn't go up over the years, and that your initial investment doesn't have much concern about spending 15 grand in one shot. If you are creative the rotor itself is about $5,000.00 without mounting or foundation, but if you were to basically put a hole in the ground with a giant pipe sticking up 60 feet for less than $10,000 you can save some serious money there. People might wonder why I know this, and it's because I just ordered a couple for my company.