Free Formatting Services
I haven’t used their ebook formatting option myself, but Draft2Digital offers free epub conversion from whatever Word document you upload to them. (Your style guide is their style guide.) They also offer a really easy-to-use front and end matter tool that helps you to insert stuff like ‘About the Author’, ‘Other Books By’, etc. into your books with minimal fuss. And unlike Smashwords, D2D is fine with you using the converted epub file they generate for you anywhere you want. (Epub is the ebook file type used by pretty much every retailer except Amazon.)
Free DIY Formatting
In the past, I formatted all my ebooks and print books myself using various tips and tricks I found online and LibreOffice. LibreOffice is a free, open-source office suite that works on both Windows and Mac. It does pretty much everything you need it to do to publish your books in every format, but there is a learning curve.(See resources below.) If you haven’t downloaded it already, you should seriously check it out.
I have also used LibreOffice in conjunction with Calibre to generate my own mobi (Kindle) and ePub (every other ereader) files. Calibre is also free to use, but donations are welcome.
Paid DIY Formatting
If you are a Mac user, Vellum is AMAZING. It can create both ebook and paperback upload-ready formats (including a large print version). It’s a Mac-only, paid ($$$) program, but if you have a lot of titles and you’re formatting them yourself, this software is a real game-changer.
I used to spend hours updating all my various book files every time I had a new title coming out (epub, mobi, print), and it was a huge time suck. With Vellum, there is only one input file per title, so if you want to update something (typo, add a link to a new book, etc.) you only have to do it in one place for each book.
On top of all the time savings, Vellum is easy to use, and creates beautiful ebook files that are head and shoulders above the very basic versions I was creating manually before to work with Smashword’s Meatgrinder system.
You can try Vellum for free with no restrictions, other than the ability to create output files. (I downloaded the trial and tested it against all my books before actually buying.) There is a cheaper version for ebook only, and a higher priced one for both ebook and print.
Some helpful links:
Smashwords Style Guide (Ebook)