i believe i got my aria from radioshack.com, and i would recommend against it. yes, i got the phone free, just paid $9.99 shipping, but the hassles involved made me wish i had coughed-up the $129 at my local AT&T.
the guy that i had to speak to because i was upgrading one line of my family plan assured me that i could stick with my unlimited data plan, (grandfathered). however, failed to realize that since i was on an iphone specific plan that it wasn't gonna fly on AT&T's end. it left my iphone 3g pretty unusable for several days until my aria shipped, and i still had to go on the AT&T site to reselect a data plan and i could not keep the unlimited.
so to me, the moral is, you get what you pay for...outsourced service from a company that is a middle-man between handset providers and wireless providers. if i could do it again, i would definitely pay the subsidized AT&T contract price so i could get service from someone who knew what to do...i miss my unlimited safety net.