I use the Sprint SERO plan. Search for it on the FatWallet Hotdeals forum. It costs $30 a month total and includes 500 minutes talk, 7pm and weekends free, free Sprint to Sprint, Unlimited data, Unlimited text messages, Unlimited picture mail, and free roaming. It also includes some Sprint TV services and Handango stuff. That is the lowest plan level. From there you can go up in minutes for more $. I haven't seen a plan with unlimited data for as cheap anywhere.

You can find info, for how to use the n800, over DUN, without incurring further charges.