Cheapest USD shipped price I have seen it for. $20.25USD Camelcamelcamel also indicates its an all time low price
http://camelcamelcamel.com/Logitech-910-001799-M570-Wireless…
If I didnt already own 2 I would grab another.
Order total(incl shipping): USD 26.09 or AUD 37.68 using the amazon conversion (using parcel pickup - may be same price for shipped to door)
Part of their daily sale - http://www.amazon.com/gp/goldbox/ref=nav_cs_gb
Today only, save up to 60% on select Logitech computer and tablet accessories. This one-day offer is valid on December 17, 2015, or while supplies last. Discount is already included in the current Amazon.com price. Applies only to purchases made from Amazon.com and does not apply to products purchased from third-party merchants on the Amazon.com website. Return to the Gold Box.
They are awesome if you've got single bloke's wrist. Locally they're ~$60