If you can buy the 16GB one ... go for it, you never know what's gonna happen in a near future with the appstore. It's quiet now but who knows...
Once you pay the extra 60-70$(I bought it in Spain and 8GB was 60€ cheaper) you won't regret it and within few weeks you won't even miss that money. What if you suddendly start working far from home and want to store tons of songs? No one else than you knows better what are you going to do with your phone but having doubling from 8Gb to 16Gb is a big jump for only 60-70$. Good luck with your final choice, whatever you do you won't regret paying for an iphone

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