There are very, very few occasions for which anonymous sources are appropriate. Do not use them.
When writing an article that is a summary of a press release, link to the press release.
Please stop pretending that “traditional journalism” had ethical standards that new media lacks. The reason some new media companies make money and some of our traditional sources do not is not so much a business model problem as a content problem.
When building paywalls, be sure that every article has a citable landing page that can be accessed for free, contains key bibliographic information to make a definitive identification of the content, and informs readers about how to pay for it.