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..
Spot on I think. If a machine/s are bought for the sole purpose of on selling to make a profit that would have to be considered commercial.
I have difficulty with the 'professional' term - to me that means someone or a business that trades or performs at an elite level. There was one trader in that green section mentioned earlier that whilst commercial I don't think should be classed as professional speaking from mine and others' experience. Just my honest opinion.
