I would say that when you buy machines in quantity to sell your are doing it commercially.

I agree Rads.

Selling off your own collection that you have collected over time or even after a couple months of playing and tinkering is IMO a private sale.

Any machines that are imported or even bought with the intention of turning them over rather than purchased for genuine want of a machine to me is a comercial venture.

Weather it's a truck load or 2,3,4 containers.

My 2 cents..