The only thing that wasn't free was my copy of WORD 2000, but it was bundled with my Windows 95 so it was free for purposes of the book.
Irfanview, an image viewer and editor is the most used free application I have. I took a photo with my camera and fixed it to the specifications for my cover with Irfanview. I used it in conjunction with MS PAINT to do the map that is in the book.
I needed a PDF file to submit. The free NITRO PDF READER, converted my DOC file into a print ready PDF.
For ebooks, some places want a DOC, or EPUB, or some other format. CALIBRE, a free ebook manager, can convert to most formats and let you view it as an ebook. Then, there is the free viewer from Amazon to view Kindle books in MOBI.
My book was made available for sale in many ebook formats at Smashwords, free, and I set the sale price. Also at Amazon for the Kindle version.
Best of all, after checking out many Print On Demand publishers, I went with CreateSpace, a division of Amazon, because it was free if I did all the work. The work, you know, includes formatting, editing, and proofing the cover and interior. It was work, but fun seeing everything come together. CreateSpace has many helpful tools and information to get all of this done. Did I mention free. A great tool is their CoverCreator.
Then I got a free website at Weebly.com. After playing with MS Frontpage, with which I had built several websites years ago, and other site creators called "easy" for days, I came across Weebly. I had my site, this one, up and running in an hour.
So, I am a published author for zero expenses. I will, I'm sure spend some cash in marketing, another story.