One important aspect one should do when doing research is checking out the price the books that sell are set at. You will most likely want to be around their price point if not cheaper when you first publish your book.
Of course an important part to that most want to know, is how much will I make for each book sold.
You can use KDP's Printing Costs and Royalty Calculator and just punch in the details of your book and it will show you.
Keep in mind in June 2025, Amazon changed the Royalty Rate they pay. Books 9.99 or higher, get 60% and books, 9.98 or less, get 50%.
KDP formula for the amount they pay you is:
(Royalty rate x list price) – Printing Costs = Royalty
So if you had a 100 page book, 8.5" x 11", that you set a list price of 9.99 on & 2.84 print cost:
(.60 x 9.99) - 2.84 = 3.15
(5.99) - 2.84 = 3.15
On a book selling for 9.98 or less and 50% royalty rate, see example below.
So if you had a 100 page book, 8.5 x 11, that you set a list price of 6.99 on & 2.84 print cost:
(.50 x 6.99) - 2.84 = .66
(3.50) - 2.84 = .66
For more details on printing cost you can see this article on KDP which goes into complete detail of it, Paperback Printing Cost. The link to the calculator above is the quickest way to figure things out.