if you are a heavy data user here, you'll be a heavy data user overseas. Get an unlocked phone if you can and sign up for a cheap temp plan overseas with a data plan. Or suck it up and pay the hefty international fees/plans your carrier charges you. Mobile weefee hotspots are for sale so check your final destination but again those probably aren't good for heavy data users. I hear t-mobile has unlimited data overseas? Anyone care to comment on that? I might switch from ATT to T-mobile if thats true.
I rang up about $150 in data usage while overseas recently. A fraction compared to what I paid for the vacay, but then my phone was severely limited most of the time with only Uber app active for rides.