GST is a goods & service tax of 10% on most of the items that are sold or consumed in Australia. If your business is registered with GST then the price will include GST for the services they provide.
If the business is not registered under GST then they will not able to charge GST. You will be able to claim back GST on goods & services if that is for business purposes unless you make input taxed sales.
You only need to pay GST on the taxable part of the sales. If your sale is separated into GST free and input tax, then it is partly taxable. The Sale of business assets is also included as taxable sales.