TM506 is the best (cheap + HSDPA). You will have no problem adding the $9.99 web2go data plan. You still might be able to get the $5.99 T-Zones plan if talk to the right CSR. I tried 3 times (online chat) with no success even though I had it in the past.
Phone History: HTC Sensation 4G | Google Nexus One | HTC HD2 | Nokia 5230 Nuron | Nokia N900 | BB Curve 8900 | iPhone 3G | Google Ion | Nokia 5800XM | Nokia E71-2 | T-Mobile G1 | iPhone 2G