A few thoughts on the mechanics of content creation... There are several things that a buyer of a kindle book will not abide - these are:
1. Obviously OCR'd text with junk characters, etc. Just say you're republishing an old book on the art of horsemanship and packaging it as "How to Ride a Pony For Little Girls", you'd better be prepared to sit down for potentially weeks retyping all of the text and crunching the images.
I avoid old books, but my workflow for such content looks thusly - Open PDF in Acrobat Pro X -> run text recognition and wait -> export from Acrobat Pro as text -> open resulting text file -> copy all text -> open MS Word -> Paste Special - unformatted text -> sit down and edit all text for a month -> open up original PDF in Acrobat -> copy/paste images direct from PDF to word doc -> save word doc as HTML -> convert with Calibre to mobi. Of course this workflow is a little abbreviated. You also need to crunch your images, add captions in word as well as create cover images at the correct size and dpi.
2. You MUST have a table of contents. People will whinge about it in your feedback if you don't. Good news is this can be done easy enough in MS Word or even Open Office.
If you're publishing on kindle, you're working hard or you're paying someone else to work hard. I still believe the benefits outweigh the negatives. It can be the easiest and least-costliest fire-and-forget trickle income model you'll find out there.
