When I self-published my first book using the print-on-demand (POD) business model advocated by Aaron Shepard and Morris Rosenthal, I had never even heard of ebooks as we now know them. I was excited just to have a book in print and to have someone actually buy a copy from Amazon!
Now, 65% of my book sales come from Kindle books. Needless to say, having as many of my titles available in the Kindle format as possible is important to me from a business perspective for a variety of reasons.
I have used iPages to do some of my own conversions. I was able to live with the ePub versions produced this way for the Nook, which I have negligible sales in anyway, but it took far too much work to produce something I could live with in Kindle format. And these books were short and had no graphics or photographs to deal with.
I have paid CreateSpace to convert some books. These conversions looked great and work great. So long as they are used only on a Kindle and not another device utilizing a Kindle app to read the book. There have been a few problems with several of my titles done by CreateSpace in this area. To CreateSpace's credit, they reconverted all the titles at no charge. Still, it caused some ill will, not between CreateSpace and me, but with some of my readers, who probably will never purchase another one of my books. Bad business no matter how you look at it.
Then there is my experience with eBook Architects. I have nothing but good things to say about these folks from Austin, Texas. They cost more than CreateSpace and some other companies I have investigated. To be honest, it is not a good selling point when I call to ask questions and the person on the other end of the phone cannot speak English or Spanish well enough for me to communicate (I live in Texas so my Spanish is, out of necessity, passable).
But, their turnaround time is excellent, they do immaculate work, and most importantly to me, an outside part verifies the quality of their work on every ebook reading device. You book comes with a seal of quality when they complete the job and you are allowed to use this seal in your marketing for the book.
Finally, every Kindle conversion eBook Architects does comes with an ePub version for the Nook as well. You essentially pay for two conversions for the price of one. Of course, you can hardly expect CreateSpace to hand you a conversion for their competition!
CreateSpace does reasonable work at a very reasonable price if your book has no bells or whistles and it not too long. Until they get the bugs worked out, just beware there could be a few problems with some Kindle apps.
You won't have any problems with eBook Architects and they stand behind their work.
Regardless, you will need an ebook version of your book to go with the POD version. With more and more people using Kindles and Nooks to read, if you want your book to have as wide an audience as possible, you need to have both types of versions available.
Do you homework before you select a conversion service. I would start with the two I just wrote about with a nod towards eBook Architects.