The Audiovox SMT5600 Smartphone has shown up on Amazon.com, for a lower price than AT&T – $219 (with a service plan).
However, the Availability is listed as “This item is not stocked or has been discontinued.” I wonder if they just don’t have it in stock yet, or if it has disappeared due to demand.
Amazon generally has far better prices than the carriers on phones, and you can activate your plan when you order the phone. Keep an eye on this page – maybe it will become available again soon.
Update: Availability is showing now as “Usually ships in 1 to 2 weeks”, but the price has gone up to $224.99 (discounted from $349) when purchased with a service plan.