AT&T has prepaid international data roaming, and the pricing is not all that bad.
Each plan is good for 30 days and is 120 MB for $30, 300 MB for $30, and 800 MB for $120. This price includes data (not voice) in over 130 countries.
Here's the link:
https://buyasession.att.com/sbd/Comm...tePlans.action