Austin Reed (a UK shop) have their summer sale on at the moment. They have mens' suits on sale at up to 70% off and if you spend more than GBP100 (one suit will likely cost more than that) they will ship the suit to Australia for free. No coupon code is required for the free delivery
Although not evident on the site now, they had a further offer where if you purchased two and input the coupon code, you got a further 25% off. I'm not sure if that offer is still current.
I've recently purchased two suits for a total of just over AU$500.
To ship to Australia, choose the country of shipping before trying to purchase anything as it will reset the site.