AT&T's international iPad 3G data plans will make you yearn for free Wi-Fi

You've just picked up that nice iPad 3G and now you're heading off on vacation in Europe in a month. You'd like to keep up with news about Icelandic volcanoes, so you're taking your iPad with you. How much is it going to cost you to do data roaming as you wander the streets of Venice? Unfortunately, a lot.

AT&T has added the iPad to the list of devices that use the Data Global Add-On Package for data roaming. If you're traveling to any of these countries where AT&T has a discounted rate plan in place, you'll need to buy one of the following packages -- preferably before you leave on your trip (all prices are US dollars):

• $24.99/month: 20 MB Data

• $59.99/month: 50 MB Data

• $119.99/month: 100 MB Data

• $199.99/month: 200 MB Data

But wait, it gets better! If you go over the purchased amount of data, you'll get to pay a $0.005 per KB overage fee (that's about $5 per MB). Wandering out of the 90 countries that AT&T has agreements with will also cost you a bit more -- $0.0195 per KB (about $20 per MB) if you're using the 20 MB data plan, or $0.010 per KB (about $10 per MB) for the other plans.

How far will 20 MB of data get you? Take a look at this old post by TUAW blogger Erica Sadun for an idea of how quickly you can rip through 5 MB, and what happens when you start paying those overage fees. Her experience of spending $24 to look at a picture of a dog on Flickr will send chills of terror down your back.

Just to give you an indication of how expensive these rates really are, remember that the AT&T Unlimited 3G plan is only $29.95 a month. It's probably not a bad idea to think about using as little 3G data roaming as possible while overseas, and then use as much free Wi-Fi at coffee shops, bars, and hotels as you can. Your wallet will thank you.