Flattr (https://flattr.com) fried something similar, but unfortunately never took off really. The initial idea as I understand it (May have changed since) is you pay a set amount per month and tip articles you read. The amount tipped is the amount you pay per month divided by the number of people you tip. Therefore you never pay more than your subscription amount.
I'd happily throw a nickel at a good article, but I don't want to have to make a per-publisher account to do so.