I thought the question was "how many machines does it take till you are a professional/commercial seller".

PROFESSIONAL to me would mean you do this full-time for a living and have an ABN etc, A Registered company etc, and know what you are doing.
I am certain companies like Mark C, Bikecity, Ken Priest, Tony Turner, Bumper all fit this professional label. All have been around for years and are fulltime experts I would feel.

COMMERCIAL SELLER could be anyone who sells machines to make money.

The key word here is Professional. You can sell 1 machine or 1000 and be professional.
Anyone can import a container and have a go.Dont mean they are Professional or know what they are doing.

When u have a Professional and Commercial seller combined, you would be dealing with the companies in green. My 2 cents worth.