Hello, I am a very experienced book cover designer, please take a look at my portfolio here on Freelancer so that you can see the quality of my work.
This is how I work:
I work with photo manipulations, each custom e-book cover you've seen on my portfolio is made of at least 10 different pictures, this allows for the cover to be completely original, which is important to authors. I usually use 1 or 2 paying stock pictures per cover; I can also digitally paint your cover instead of doing photo manipulations.
If you wish to work with me I will begin to develop a series of drafts showing the kind of cover I suggest based on the information you give me about your book and on your own ideas (there is no limit of drafts, I'll keep on sending them to you until you're satisfied with the images to be used, the composition of the cover, its color palette and font).
I can adapt to your time frame, of course.