I recognize you from the 2011 Rutgers 1-on-1 thread - I was there but arrived Sat so missed the Blueboarder dinner. I've retold many tales for educational publishers for work-for-hire books and other projects and have used the online sources writerdebm listed. You might be interested in the new epicturebook venture, uTales, which is launching Nov. 2 as an Apple App. There are already some retold tales on the site and they welcome more. As an author, you can collaborate with an illustrator. A number of conventionally-published writers have books up. There is editorial oversight; books must be approved for publication on uTales and Emma Dryden currently oversees the approval board. Part of any proceeds benefit a charity called Pencils for Promise.
Congratulations on your story in Highlights!
Best wishes - Frances