I just found out that my iPad 2 got a 3G Sim card slot and am wondering whether to take up a plan. Like someone said, getting more confuse after reading thru some of the posts here.

Got only 1 question for the sifus.

Is there a plan where I can buy whenever I need?

I don't want a monthly committed plan but I do want a Sim card where I can purchase the data when I needed without having to reactivate, call customer service, etc.  Also the purchase of data should be easy (eg just make a phone call and activate instantaneously or alternatively, the sim card still goes to the provider's homepage and I can top up then).