You are correct that Poe's The Raven -- first published in the U.S. in 1845 -- is in the public domain. You are free to modify, illustrate, translate, publish, animate, or even rap to Poe's fresh rhymes. You can claim copyright in any original, non-trivial contributions you add to the poem and you are also free to price the work as you wish (though $9 might be "poetic justice" as that's what Poe was paid for the poem - approximately $250 in today's dollars). If you provide illustrations, you'll also be joining a remarkable group of illustrators including Gustave Doré, John Tenniel, Harry Clarke, John Rea Neill, Edouard Manet, Lorenzo Matteotti (who collaborated with Lou Reed), and Gahan Wilson.
|left: Edouard Manet, center John Rea Neill, right: John Tenniel|