If you are purchasing secondhand items with the intention of resale - you need a Secondhand Dealers Licence. This has been the law for decades (our family were first licenced as Dealers in Qld in 1983 - and hold one of the earliest current licence numbers).

Unfortunately ebay participants and lots of people commenting here have no experience - they simply "follow" whatever the other bloke is doing - that doesn't make it "right" or legal and lawful.

The Office of Fair Trading has really cracked down in Queensland in the last year or so - and lots of people who had previously relied on a wing and a prayer are finding out compliance with the law is actually necessary.