I am willing to pay for premium Newsblur features with bitcoin, but not credit cards. Unlike credit cards, there’s no possibility of chargeback fraud, so newsblur will be able to keep more of the money. Reddit and wordpress accepts bitcoin. Why shouldn’t newsblur?
If you’re going to use bitcoin, you probably want to use a payment processor. I heard bitpay is a good solution. They deal with all sort of stuff for you such as currency conversion, direct bank deposit, and so on. Although you could build your own payment processing solution and not have to pay fees, I doubt it will be a good use of developer time.