I'm pretty sure it used to be $75 and now it's $200. It was in the tech news headlines a while ago. They even jacked up the retail prices of some cheaper phones because the early upgrade price ended up being more than retail price.
Hold on, I just checked the website. It looks like an early upgrade for the iPhone is only $279. But the Atrix just says $499. Should I call and see whether they'll give me an Atrix for $279?