Stamp duty on a business sale depends heavily on where the business assets are located, and the answer is genuinely different from state to state.
Technically, transfer duty on business asset sales varies by jurisdiction. New South Wales and Victoria have largely abolished duty on business asset transfers other than real property, while Queensland and Western Australia continue to apply it to assets including goodwill and intellectual property. Real property attracts stamp duty in every Australian jurisdiction regardless of how the wider transaction is structured.
This state-by-state variation makes the location of business assets a real factor in how a deal is structured, and getting the apportionment between dutiable and non-dutiable assets right in the sale agreement matters more than it might first appear.
What you as a seller should ask your tax adviser: exactly which assets in this sale are dutiable given where they are located, and whether the sale agreement apportions value between assets in a way that has actually been checked against the relevant state duty rules.