Just to be perfectly clear, i repeat: Donating by sms (or text, whatever you want to call it) will cost slightly more than donating by paypal or card. I'm not sure exactly how much the fee is, but from what i've read on onebip, it may be around 10% of what you donate. So if you want to buy 20$ worth of points, you would have to pay 22$ to cover the donation plus the fee the company charges.
Just making sure everything is clear for everyone.
EDIT: To be 100% sure of the fee since i can't specifically find it on their stinkin website, i'll need someone to test it out for me...like donating 1$ off their phone or something, and i could check the reciept afterwards.