HI,
Long ago, I took a tour with Culinary Historians of the original Maxwell Street, which included a visit with the owner of Jim's Original.
What were his most profitable items? His proprietary Polish sausage followed by the bone-in pork chops. His least profitable was the lowly Vienna hot dog probably because you are not only buying the dog, you are banking on their market recognition and support. Why else do some businesses keep the Vienna signage and don't offer Vienna dogs. They know what their customer's consider quality, even if it is not really provided. If you can offer something unique, proprietary and desired by your customers, then you will have found a great profit center.
Jim's also found it more economical (which translates to profitable) to pickle their own sport peppers. He hired someone once a week to peel hundreds of pounds of onions to be freshly slice and grilled as needed. A lot more processing and hand work than may be expected, but in business pennies count.
At Hot Doug's, his Chicago hot dog is a loss leader at $1.50. You get into the exotic encased sausage, proprietary=profitable, they you are $4 and up. Plus his flare for marketing and attracting the press on the cheap is phenomenal; which is intended as a compliment.
Where are you considering having this business?
Regards,