Recently I wanted to use a Creative Commons image in a project which was a bit blurry as to whether it constituted commercial use or not, so I contacted the owner and asked them as they had specified non-commercial. They asked for payment (which is of course their right), but I didn't have a budget so I declined and found an alternative image.
Similarly I was looking for an image of a bee a while ago for a school project for my daughter and found a nice one, but they wanted $200. After I had stopped laughing I went and found a free alternative.
And this is the problem for any online commodity - there is always a free alternative available. It may not be as good, but it'll do. I apply the same approach to articles and referencing - if I have to pay to access your article, I'll find an alternative which says more or less the same thing, and which I can access freely.
The question for anyone wishing to charge for an online product then is this "are there free alternatives available". If the answer is yes, then forget charging.
In this respect I was reminded of Michael Corleone in The Godfather 2. Senator Pat Geary is attempting to extract a bribe from him and Micheal responds:
"You can have my answer now, if you like. My final offer is this: nothing"
Corleone has violence and intimidation to back up his offer of nothing - we have abundance of alternatives. I'm not arguing whether this is morally correct, maybe we should pay, but the point is about behaviour.