The model that the author is working on at Gluejar Inc. is crowd funding. It's analogous to the method that public radio and public television is funded in the US, except that every book that's to be released with a Creative Commons license has a fund drive of its own. Once the producer's price has been matched by reader pledges, an open-access e-book is released. The pledge drives are managed by a website.
Authors have used crowd-funding websites such as kickstarter.com -- http://www.kickstarter.com -- to cover the expenses of completing a new book. For example, Mur Lafferty raised over $19,000 from more than 250 backers to fund book design, cover design, and e-book conversion for a fantasy audio series. In a few cases, the projects use Creative Commons licenses. Stephen Duncombe, a Professor at NYU, has been trying to raise $3500 to fund the further production of an open-source version of Sir Thomas More's Utopia, which is distributed with a CC BY-SA license. (Of course the underlying work is in the public domain, but the new translations, annotations, and commentary is subject to copyright.)
To get a better idea of how crowd-funding might scale to large numbers of books, consider the author of a romance series. Rights for the earliest books in the series have reverted to her, but there's no cash to convert the book to e-book formats. She contacts the pledge-drive website, and enters an offer to release the first book under a Creative Commons license in exchange for a lump sum payment that she considers to be fair and which covers the conversion to e-book. Fans of the series can then go to the site and pledge support. If the author's offer price is met, supporters get billed, and the author gets the payment. The resulting e-book file is sent to all the people who have pledged, and put on a feed for the rest of the world to pick up. Since the e-book is now Creative Commons licensed, it can be redistributed for free.
In another scenario, a reader launches the pledge campaign, perhaps someone who has found the book in a library. The library metadata is pushed to the pledge-drive site and other fans can pledge their support. Eventually, the pledge amount gets big enough to attract notice from rights holders, who can then show up, deliver the e-book, and take the cash off the table and divide it among themselves.