The only difference between a legitimate traditional publisher and a legitimate electronic publisher is that the product is in electronic form, rather than paper. For centuries, geese suffered for the written word. Then trees did. Electronic publishers torture only electrons. Presently, the vast majority of e-book authors have traditionally published books on their resumes.
Prices vary from publisher to publisher.
Which is more than you can say for most paperbacks and any hardcover these days. So, I buy an electronic book. Number One, pick a format that will do what you want it to do. My publisher offers books in PDF format or RTF format. Both of those, by the way, are compatible with either Mac or IBM-compatible PCs.