Toyota Camry 2006: Noisy rattle in manifold

Since 2011 our 2006 Toyota Camry Altise since has had a really noisy rattle in manifold. Toyota knew this was a problem, but didn't suggest anything until we mentioned it. They informed us that it was the diaphragm in the manifold and it was okay to continue driving. We were quoted $800 for the part, plus installation at the time. It seems others have had this issue and Toyota have known it exists. We feel the price is excessive and a fault with the vehicle which should have been rectified by Toyota in the beginning. Has anyone else had issues with this?