I've published several book on Amazon KDP, and just want to mention you don't need Latex or markdown or anything complicated. Word works fine. You can pay someone on Fiverr to convert it into the formats you need for $10, or you can go with slightly more expensive services ($60ish) if you want someone to spend some time making it look nice.

This is for straight narratives or non-fiction books. Things with more complex layouts will require more work.