Hi watchman,
Buyers don't always do lots of market research, so if you are selling in a different place (like eBay) for a higher price, you can still get some sales - even though the buyer could get it cheaper going direct to OO.com
However, you probably shouldn't rely on OO.com for all your products, but use a couple of other suppliers as well so that you are offering a unique product selection in a particular niche rather than just an exact replica of OO.com.au
Also you can add marketing perks (like a freebie, free post, great customer service and the likes...) to help you increase your sales or traffic
Hope this helps. Cheers! :)