Bose S1 Pro Portable PA System w/ Rechargable Battery $649.35 @ Bose Australia (Hack Required)
I'm using the same method by using the Honey Chrome extension mentioned in this post here
I've used this PA speaker before, really good portability and audio quality is as expected of a Bose product.
Use PayPal as the method for checkout.
Seems to be historically lowest price of this item.