I picked up mine from a market. I really don't recommend this method as I had to spend ages trying to find the one seller who both was fairly reputable (so I could return it if it was a fake) and who understood that R4s are crap (most of the stall-holders will just insist that whichever R4 their peddling is the only real R4).
And even then I paid through the nose for it.
Actually, I remember all of the other stall-holders who did stock the AceKard 2i. They all had it off to one corner and marked at a far lower price than the R4s! I laughed so hard later!
Anyway, getting back to the point, the Aussie dollar is doing pretty well against the US dollar right now, so I highly reccommend getting one off an online store that charges in USD (a lot of them have free shipping). You can get an AceKard 2i at a good one for about $15 USD, translating to only about $17 AUD! I don't know what the best store is, but I'm sure someone here will post an answer.