Again, you're not providing us with details. Is this a single or a family plan? How many minutes per month? Does that $130 include texting?
Like chas stated above, the absolute minimum you can get away with is $60 a month. I just checked AT&T's website and I don't see how you can even get up to $130 a month. Unlimited calling is $70, iPhone data plan is $30, and unlimited messaging is $20, for a total of $120. The only way I can see you getting up to $130 is if you add in things like AT&T Navigator, Roadside Assistance, or VoiceDial.
Also, you don't have to purchase through AT&T, you can just walk into an Apple Store, buy an iPhone, and create a new plan with the options you want, ranging from a bare bones $60 to $120 for unlimited everything, or you can do the same thing online at either the AT&T or Apple website.