Sean Baker’s “Tangerine” was

Sean Baker’s “Tangerine” was shot using an iPhone 5; other films have been shot using a Go Pro or similar device. So it can be argued that a “professional” camera is a camera being used by a professional, even thought it is thought of as a “consumer” camera. On the other hand, “professional” cameras — that is, video cameras typically used by professional videographers and thought of as appropriate for film/video work — typically start at a cost of around $1500 and can exceed 10 to 15 thousand.
If I were you, with the dream of starting a “movie company,” I’d save a bit more and buy a high-end consumer camera, which could serve you very well in the early stages of your business.