This is not an exhaustive list of print cost calculators and royalty structures for print-on-demand services by any means, but it does focus on the top

I have assembled a handy single-sheet reference to help you choose the right trim size for your book.  This is doubly helpful if you want to

Here is a template that will help you perfect your 6×9 full-cover design for your paperback book.  This is a 2-part overlay: front and back with bleeds