I used the "T-Mobile Even More Plus™ 500 Talk with FlexPay®" and added the featurephone internet "service"... I could only get edge anyway because of t-mobile's weird UMTS frequencies in the USA. I just had to set the proper APN and it worked (only edge, but that's just because I had a European GSM phone)

p.s. I used google voice for texting, no need for stupid text message plans

What plan is that? I'm on tmobile and just upgraded to a Nexus S and all the unlimited internet plans seem to hit 70/mo or above. $30 for unlimited internet, plus $39 minimum for the rest. Would love to grab your plan if possible.