Re: At or below cost
I know it's probably not what you want to hear but my best advice is to give a copy each to a handful of friends and let them spread the word on your behalf. Having considered it, I suspect you're right - a engaging "cover" on amazon might get you a few sales (if you, or the publisher, are going to be paying the cover artist anyhow, it certainly wouldn't hurt to use it for the ebook as well). Suggesting your book to a relevant group on goodreads.com might help. In all honesty, I don't envy your position but if there were an easy answer, everyone would do it that way.
Hell, if you're writing fiction, hand out a few copies to people on a bus or train. As the legions of Game of Thrones fans attest, wanting to know what happens in the next episode/book will drive sales.
If it's any help, aside from friend recommendations, the first time I've picked up an author's work were from:
- fiction: wandering around the local library, or reading something else the author's written (an article or similar) and enjoying their style.
- non-fiction: seeking reference material or additional perspectives (for learning different aspects of programming) or a lay interest in the subject matter (astronomy, history, physics, neuroscience).
I'm probably a bad example to extrapolate into a general, book reading audience... but how one person goes about finding books.