People are constantly snacking, and the use of popcorn machines to create a part time stream of revenue is still a great money making business. It is almost pure profit, as the supplies, and overhead are almost non existent. There are some major cities that it is fairly easy to set up a daily full time business, they have to be totally pedestrian friendly, and have a large population for any profitability to come to fruition. Buying a new commercial popcorn machine is going to run a person minimally about five to six hundred dollars. This is the 8 ounce size popper, and works best for street vendors.
There is also a huge used popcorn machine market, and usually these can be purchased for around two hundred and fifty to three hundred dollars. The only drawback will be that there is no warranty, and if it breakdown right after you purchase the unit, it will be all out of pocket expense to repair. A vending cart will also run about two to four hundred bucks, and you might have to have it customized with paint or vinyl signage.