Is there anyone with affordable AT&T 3G plans for iPhone?

As you said that you want to know the data plan for AT&T mobile so I am providing you the detail of the best plan available on the market.New iPhone 3G unlimited data plan $30 per month.

It is right, with higher data speeds, AT&T will be charging higher data fee. Where the first generation iPhone was blessed with a relatively cheap $20 dollar for a month unlimited data plan, all iPhone 3G hopefuls will have to sign-up for a $30 dollar per month unlimited data plan, the $30 iPhone 3G unlimited data plan must be added to qualifying calling plans. The new high-end plan, called Data Pro, gets you 2GB of data use for $25 per month. If you go over 2GB, you'll pay $10 dollar for each 1GB increment. For example, if you use 3.5GB, you will pay $25 dollars + 10 + 10, or $45 dollars for the month business users can expect to add $45 dollar on top of their calling plans to get unlimited data on their iPhone 3G.