AT&T is running an exclusive online offer that allows you to save up to $100 on select phones and accessories as well as free shipping on your order. The Lumia 900 is $99.99 on AT&T website. Once you add the device to the cart and select your plan, the $100 discount is automatically applied, leaving you with just the activation fee to pay. Check out the source link to begin shopping.
If you’re already an AT&T customer but are looking to renew your contract, Walmart has the Nokia Lumia 900 for both new and existing customers for $49.99. That’s not as good as free, but it is 50% off.
source: AT&T & Walmart (Black) (Cyan)