Usually it costs me around $1000 for a ghost written book. Book is around 35k words (3c/word). Editing is 1.5c/word or flat rate depending who I get to do it. Covers are usually $250 for ebook or double if I get physical.
I use vellum to format ($250 one time). Requires a mac. The company I use will sometimes do this for me for free.
Marketing beyond email list is then either book bub if I can get in or amazon ads.
Mailchimp/digitalocean for email list/Wordpress site hosting. Google Apps for email. Those are my reoccurring costs.
Break even is usually 800-1k copies sold @ $2.99 list (I earn 70% of that). Plus whatever I spent on marketing. Anything outside 2.99-9.99 Amazon will only pay 30% royalties. I earn roughly a dollar per book read via kindle unlimited.
The first few books will take a while to earn back. Building your following/email list is the most important thing. I use it for engagement. “New book coming soon! Giving away 25 advance reader copies enter here”. Then before release “pre order now. Here is the feedback from those that won a free copy.” The surge of reviews/early sales helps boost Amazon ranking (new readers) as well as to quickly earn back what I spent producing it.