I have found that there are many collectibles that get far more bids if you list them on the American or UK ebay sites. There are some collectibles that Australian really aren't interested in or they are not prepared to pay for. By marketing them to an international market and offering Pay Pal as a payment method you can make your listings more appealing to overseas bidders.
For example, I sell Victorian chromolithograph scraps on the American site. About 95% of my customers are NOT from Australia. I list my items to finish at times that suit my American and European customers, and at the end of the auction Pay Pal gives them a safe and convenient way to pay. I am then able to use the funds in my Pay Pal account to buy more stock from overseas and Australian sellers, or I can transfer the total into my bank account. It is great fun converting US dollars into Australian dollars!
I have noticed some Australia sellers list items that are popular with European buyers on the UK ebay site. Certain postcards, fine china , vintage toys etc. fetch a far higher price if sold outside Australia. It is also good to keep in mind that one pound in about $2.50Au, so as a seller you can make a far greater profit. As a seller it can only work in your favour to have as many buyers as possible see your item and bid. So next time you go to a market, antique shop, garage sale or school fair keep a look out for collectibles that may appeal to overseas buyers. That said, Australian bidders are great too!