Hi everybody, I'm still around.
I got caught out really badly in similar circumstances.
The seller didn't advertise his shipping costs and I neglected to ask until I'd committed to buying the item. The shipping charge was US$78.00, yes that's US$78.00! Being also in Australia, and having no idea of postage rates in the US, I paid up, only to find (when I received the item) that postage was actually US$35.00! All emailled requests to the seller for an explanation were ignored.
My policy now is not to deal with "commercial" sellers in the US.
The moral of this story is: always ask for the shipping cost before bidding if it's not mentioned in the listing or you may (will!) get burnt!!!
GG