Well, there are a couple of key questions that must be answered to give you the best possible, no B.S. answer.
1) Are the ebooks PLR-based, or created specifically for and/or by yourself,
2) Are you willing to open up to multiple markets by offering differing electronic formats
If the answer to 1) is personal, non-PLR source, then the options available from 2) are
valid, and quite profitable (and residual).
First, take the ebook and convert it to a print-on-demand ready book. Use whichever
source of service you feel most comfortable with. This will function under a unique ISBN,
which some places include as part of using their "publishing" service.
Second, make it available through Amazon's Publisher program. They now have
print-on-demand services available, having acquired createspace.com, so you might
accomplish a considerable part of market positioning diversification through them alone.
Then, be sure to prepare a cover image to use at introduction, and one including the
Amazon Bestseller badge. Use a limited free offer to get on top of the bestsellers
listing, update your cover image, and raise your price for awhile.
~ T