T-Mobile is having a promotion (on-line only, not in stores) of their
prepaid phones with $25 airtime cards included.

The Motorola V195, ($39.99) is a good basic quad-band phone to take
overseas to use with prepaid SIM cards. I bought one (unfortunately
prior to the $25 promotion) and I had it unlocked by an unlocking
service ($15).

I can't use T-Mobile where I live as the coverage is terrible, but it's
a good phone to use with other prepaid GSM services on AT&T's network,
i.e. 7-11 SpeakOut. I was using a very old Motorola P7389 GSM phone
which was problematic because prepaid providers in some countries send
out text messages with passwords, and that phone could not receive text
messages.