I agree with Typhoon and Tom, but offer this perspective, one from someone who put the safety of the law aside to open a small business. Several things gave me confidence - my husband continued to work so we always had a good income; we had enough money to purchase the real property in which to operate the business; I did not have to hire a lawyer, real estate agent, accountant, bookkeeper, barista or janitor since I performed all those roles myself; and we had a healthy bank balance so that if the coffee shop failed, we were not going to be penniless.
You appear to be the complete opposite of me. I would echo Tom's advice that starting and running a small business is very risky, very stressful, very time consuming, and very emotionally draining. Over 50% of new businesses fail so your chances of failing is rather high especially if you should be spending most of your time pursuing your aviation goals. If you wanted to run even a small drive through espresso stand, I know the start up costs will run you about $3000 for the stand only and $10,000 for all the equipment, with the espresso machine being the most expensive. Then you have to hire your bikini baristas because nobody would patronize your place if they saw a starving wannabe pilot making their caramel latte.
However, I re-read your post and took notice of your idea of vending machines. This is a low cost way of making some extra money. The cost of the machines themselves is not prohibitive. You would need to find good locations and have to make time to service the machines, probably daily. Not a bad idea really.