i've been noticing more websites not including GST in listed prices, which, to my understanding, is illegal unless you're advertising exclusively to other businesses:
Businesses must display the total price of a product or service as a single figure. This price must be the minimum total cost – the lowest amount a customer could pay, including any taxes, duties and unavoidable or pre-selected extra fees.
here are two websites i've seen doing this in the past week alone - red hat and patreon. patreon in particular is in no way aimed at business-to-business transactions.