Probably the only authority that could answer that question is the australian taxation office,i guess at tax time they decide if 1+ container makes you a commercial seller or 5+ pins makes you a commercial seller,but when it comes to the ATO i guess it will be whatever suits them.They are going through ebay at the moment and according to them any sales over $20,000 a year they are looking at so i guess thats the answer to how many sales till your a commercial seller? $20,000 worth.