"How do you make a hot dog stand? Take away its chair." My 9 year old neighbor
If you're entrepreneurial, a hot dog pushcart is a pretty inexpensive way to start your own business. For $20 you can buy plans on the internet to build your own cart from about $500 worth of parts. For less than $2,000 you can get a pretty nice professionally built cart, and for $10,000 you can get a fancy trailer in which two people can stand and work. There are even large trucks with commercial kitchens available in the $100,000 range.
The wholesale cost of a quality hot dog is about 20¢, a bun costs about 10¢, and the condiments cost about 10¢ per sandwich. That makes your cost about 40¢ each. If you can move volume, you can buy for less. Typical resale price in Chicago is about $1.95, so your gross is about $1.45 per sale.
If you sell 200 hot dogs per day, 360 days per year (hey, take some holidays off), you would sell 72,000 dogs per year and could gross over $100,000 (not including soft drinks, chips, etc.). That's cash money. No credit cards or checks. To stay open this much you'll need a high traffic spot, indoors, and employees.
Subtract your overhead: Payroll, napkins, propane, rent, license fees, freebies for the cops, and other supplies, and there's still a decent profit for a pretty small upfront investment and a lotta work. Oh yes, don't forget to subtract from the profit the dogs you eat yourself.
Here are some suppliers who sell pushcarts and vending trucks: