One of the advantages of debit cards is that they can be used as a way of buying goods over the internet.  This can mean that they can be used as a way of getting goods from a far wider variety than can be got from shops.  This can mean that there is both a wider variety of goods available while there are also goods that tend to be sold at a lower price.   This will mean that a debit card can be used to get goods from abroad.
The way in which debit cards are used over the internet is actually the same as the way that credit cards are used, despite the fact that credit cards and debit cards are actually very different.  Debit cards and credit cards use the same system to charge their accounts, so that a vendor will not really care whether a person is using a debit card or a credit card as the money will still be in their account reasonably quickly.

Debit cards can also be used abroad due to the wide acceptance of VISA and MasterCard cards around the world, and to the fact that almost all internet shopping carts will accept debit cards as well as credit cards.  There are two further issues with buying goods abroad using debit cards, and those are foreign currency and shipping costs.

A vendor will be paid by the debit card provider in foreign currency while the debit card holder will be charged in Australian Dollars.  This will mean that the cards will be converted at the rate that prevails at the day.  Although the conversion rate tends to be a reasonable rate, the credit card user can be charged a foreign currency fee that can be as high as 3% of the transaction value.  This can mean that the saving on the foreign good will not be as high as it would look when comparing the prices with Australian websites.

There are also shipping costs.  In almost all cases where the good needs to be shipped, it will cost more for shipping a good from overseas than it will cost for shipping a good from Australia.  In some cases a website will not ship to Australia, although with most vendors they will simply charge a higher fee.  This can mean that there is an additional cost to the buyer.