1) Check out your market. You dodn't (like most here) cite your location, but, e.g., I live in McKinney, TX, so the first thing I'd do is go here
2) Notice - all have the equipment, but the 'overhead' varies from permanent, free-standing to carts.
3) I'd start with a cart (or an easily dis-mandible 'shack') in the parking lot of a busy summer location at a place where your business augments, not competes, and where people are waiting, e.g., a busy car wash on a commercial strip.
4) Are there undeveloped lots on busy thoroughfares where you live? If so, the short-term land rent will be cheap and you can either rent by the season or also have seasonal fireworks and Christmas tree businesses. Do that and you'd bank (or hide) more than you'd believe.
5) In any case, never buy new equipment. Used is only pennies on the dollar; shine it up and locate a good mechanic to make it run as new and be on-call to keep it running.
I can't think of anything more fun than to sell something with a COGS of pennies for $3.75 and have the customer walk away smiling and happy!
And get one of those little 'square' card readers; a lot of folks never carry cash anymore.
Anyway, Welcome to Roadfood!