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Recent European experience:

In Italy you can buy 3 (tre) mini sim for Ipad (only 5 euros for 3 GB / month). All other companies had some activation problems especially Vodaphone.

In Germany - no such thing as prepaid unless you have German bank account. The only way is to buy regular sim with data package and cut it.... its about 25 Euros.
 
You know yourself that there was no chance to get a 3G w/o a contract with SB.
Actually you can. You can pay a month at at time if you want.

I believe that the cost is somewhere around 5,980 yen per month. It's for 2GB of data.

If you sign up for a 2 year contract you get unlimited data for 2,910 yen per month after rebate.

In my case, I figured that I would use it more than 6 months out of the year (break even point) and went with a contract. I'm on the go a lot, and for some reason the little WiFi alert boxes bug the heck out of me. So normally, I just go via 3G since is works just about everywhere like on the trains, in my car, on the bus, etc. Plus I like the GPS feature. Just used it for navigation yesterday evening.
 
Great info - Thanks! I'm leaving for Turkey in a couple of weeks. I will be in Istanbul and visiting small towns on the south-west coast near Marmaris. Can you give me a few more details regarding carriers and cost? Would I have any difficulty in purchasing a plan as a non-Turkish resident?

Great! I'm currently in Ankara, but I can truly say that Istanbul is a magical city. Enjoy your time over there. And don't forget to take pictures for friends.

There are 3 carriers available in Turkey right now, all GSM and has good 3G services. Most popular one and the most reliable one is Turkcell(with market share over 50%), followed by Vodafone, which is cheaper but not as reliable as the first one. I'm using a Turkcell data plan with 4 gb limit, costs around $30 with all the tax included. They don't have any pre-paid data plans .I was able to get a commitment free service with some help from a colleague. Turkcell is the best one here, with excellent coverage and fast speeds. Far better than At&T for comparison. They require passport from foreigners and $20 one time only service fee. Prices are like 1 gb for $20, 4gbfor $30 and 8gb for $40.

Vodafone might be a better alternative for you as they have actual pre-paid data plans. Their 3G coverage is not as good as Turkcell, and sometimes 2G only in rural areas. Pricing is a bit different, 1 gb for $8, 5 gb for $30. They have plans such as hourly, daily or weekly unlimited. However, you may need to send a text message in order to activate these, I don't exactly know.

Third carrier is called something like Ave, and I have no idea about their prices. What I've heard is their 3G is the worst.
 
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