I've had a long-term working (and writing) relationship with Iceberg Publishing (www.icebergpublishing.com), and having produced dozens of images and videos for their books, I've learned many tricks to economize my time, while keeping quality high. I make this experience available to writers and small publishers too, and to help provide guidelines for what costs might be for independent authors and small presses, here are some examples:
Defense Command: "Tapestries of Blood" Cover Image (Cropped Image)
$200 - $250 Canadian
Defense Command: "2235 Omnibus" Cover Image (Full Cover Image)
$250 - $300 Canadian
Seas of Sand: "Finding the Range - Anthology I" Cover Image (Back and Front Covers)
$350 - $400 Canadian
The Equation Series: "The Destiny Equation" Cover Image (Cropped Image on the Back Cover)
$150 - $300 Canadian
Unfortunately, I do charge more when working with large publishers, or other industries... but for authors and small presses, it's basically work at minimum cost. Once I do an image, I pass all rights for it to the customer, and if we do multiple images of the same ship, additional discounts might be available, depending on how complex (if you need multiple angles for a ship schematic, for instance).
So if you're an author trying to get your vision of one of your ships onto a book cover, or a small press looking for quality CGI that you can afford, I'd like to help. Email me if you have any questions!