I own a preponderance of horror related paraphernalia, pictures, and enough blood graphics to drown a vampire movie and yet, I don't write horror novels. Which means those pictures of my skulls, tombstones, and dribbly candles were mostly left to rot until I discovered a catalog self publish site.
Called SelfPubBookCovers, people can create and then upload to sell book covers for all the self publishers in the world.
I opened up my own shop and went a wee bit crazy with some of my back catalog.
Or, if you really like one but want a color changed/piece moved/better font choices, just get in contact with me and I can come up with something. Plus I'd only charge $50 since that's all I'd make from the site.
If you're looking for some horror ebook covers, a little dark fairy tale, fantasy, or trees (always with the trees) come and have a peek.