For those who used this tip to get a US itunes account, here's a good place to get credit codes. $10 for $5.99, $20 for $11.99, $30 for $17.99.
Also, don't forget, make your US address one without state tax, eg. Alaska, not New York, to get the most out of this. Google the state and "zip code" to find a working one.
I have used this same seller, but on ebay. They now have opened their own site. After paypal transaction, they will email you the code in as a GIF image. I've bought $80 worth of credit, and am very happy. That's equal to $135 AUD worth of value for ~$52 AUD for music (99c songs vs $1.69 plus conversion at current exchange rate).
Plus movies and TV shows (Comedy specials running 90 minutes are available for $1.99).
An unaffiliated website like this might make you raise questions. Of course, if you're worried but simultaneously tempted, try a $10 code first and see that they deliver.
This web site has some "problems"
1. the vendor calls himself Chaos Gamer
2. the contact email is Yahoo
3. Payment by paypal only