Seems that you never know in which countries the mobile data works and is inexpensive.
For the past week, I have been in Tanzania (Dar es Salaam and Zanzibar) and purchased a VodaCom prepaid sim card at the airport upon arrival.
I believe that the price of a SIM was 4,000 TZS ($2) and unlimited mobile data for a week an additional 7,000 TZS ($3.5). Decided to ad four thousand for a call or two that I may need to make.
To be honest, I have really been surprised how fast and reliable the data connection has been. It has saved my life at two hotels (Holiday Inn and DoubleTree Stone Town) that had issues with their internet. You cannot fault having 3 MBPS up and down tethering using your cell phone.
Couple of weeks ago, I was in Brazil and will be back sometime next week. As a foreigner, you are forced to purchase super crappy packs with 10 MB daily limits etc. I got my local friend to open a prepaid line under his CPF and I ended up paying $7 for every 450 MB of data consumed.
The problem was that every time after I had exhausted the 450 MB limit he had to call Claro and unsubscribe from the data package before I could order another for 22 reais or so.
May be the reason for the speedy data in Tanzania is that quite a few people seem to be using older phones better suited for talk rather than internet.
It really is surprising that you can get proper access in a country such as Tanzania compared to some far more advanced countries where it can cost an arm and leg.