It also goes how much scrap metal etc you plan to cash in,
Once you get over a certain $ figure they ask for your ABN number,if no ABN number the the scrap metal base price goes down, ie: copper on ABN $1.a kilo ,Copper with no ABN 50cent a kilo,(not real figures)
Best to call ahead and ask the ABN limit and scrap it in smaller batches, means more trips to the scrap yard but more coin in your pocket,
Matt