I'd personally stick with the Motorola v323i ($170) or the LG 245 (now $130), or maybe shell out another $60 for the Motorola Razr v3m, but then again, these offerings put Pocket on phone parity, generally speaking, with the other unlimited carriers. Additionally, they look to be getting the Razr2 v9m and (as mentioned before) the Kyocera E1000 "Deco" in the relatively near future, judging by the references to these two phones on the ringtone\media download page on their site. Which would mean their phone selection would be every bit as high-end and current as anyone else's in the unlimited market, even comparing favorably with contract carriers as long as you don't count smartphones, which can be flashed to Pocket anyway if there is a need to do so.
Also, sorry for not tagging posts recently. I'll get back into that, and retroactively tag posts when I get the time to do so.