Be sure to understand the difference between a ‘Broker’ and an “Agent”, a Broker acts for the client, in this case the Body Corporate. The Agent is an Agent of the Insurance Company and represents them, the Agent can have an Agency agreement with several insurance companies. The Broker can have a Contract/agreement with the same Insurance companies.
You should also check regarding the commission that is shown in the disclosure document, you should be able to negotiate with the Broker to have the commission rebated and the Broker will charge a fee for organising the insurance.
This can reduce the cost as the rebated commission reduces the base premium.
It is worth paying the Broker the fee/commission, they have the knowledge and expertise to assist, especially if there is a claim, and of course they are acting for you the BC and negotiating with the Insurer/underwriter on your behalf.