Personally I'd go and find the nearest cyber cafe.  They seem to be about in most towns, it would be cheapest option I'm sure.  Datacard or Phone will be hugely expensive and not worth the hassle. 

Does all your work require you to be online, or can you collect the online data that you need before going, if so do as much prep that requires internet before you go and then work offline for as much time as possible, and nip into the cyber cafe when you need a connection.