No idea -- I very rarely shop online, and I've never dealt w/ BBTS before.
Edit: I just checked - the default option is USPS Air Mail, which is US$13.99 plus $5.75 per 455g... so mebbe about $20. The preorder price for the two Voyagers is $44.99, so it'll cost at least $64.73 including postage - which makes it $32.37 per Voyager. That's still pretty damn cheap by Australian RRP standards!