Ebgames.com is one of the best sites for purchasing video games in Australia. Their prices are really good, $39 for a preowned Nintendo DS lite. Buying from them online is easy, you do not need to be a member. You can purchase standard shipping or express, but it is better to just get standard. Their online store has all of their products, telling whether they are in stock or not and prices. There are also some online deals which is worth it. They will also accept Paypal and will take payment immediately. Check them out

I think this is one of the best sites to purchase games. This site has more than just games, but I've been using this consistently to purchase PS3 games that are way cheaper than EBGames or JBHiFi. The shipping cost on this site is good at under 2 GBP, and with the strong Australian currency, the prices are much more competitive. Note: Prices may change depending on currency.

Approximate cost: $30