You might want to go with a graphic designer. I know someone who may be able to work with you. I have two designer I work with and are both reasonably price.
firstname.lastname@example.org and email@example.com.
You may want to contact them and could help build an e-book cover for my site. If you go to cherubdefense.com, you'll see some of their handywork. The scrolling signs were done by osironlore (Nathan) and if you go to my coaching page, the graphics were done by hazy (Bryan).
Tell them, Elmer sent you.
Thanks guys for your responses.
Consider www.elance.com. Affordable covers are available from designers there. Be sure they have experience with what you are looking for and a portfolio of work (you like).