I think I have answered this question at least once already!
You now seem to be talking about an ebook, the length of which has very little to do with its price. I generally go for $4.95. Others favor $3.99 or even $2.99, and there are a depressing number of people who are desperate to give their work away for 99 cents, thereby ensuring that nobody will value their work.
If you have written a ground-breaking work of military history, you might be able to get a bit more for it, but I have never gone above $7.95 for an ebook, even in the glory days when the Kindle platform was paved with gold. Now you are competing against literally millions of desperate self-publishers.
u(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook.)
Sorry Sir, should I chose 35% or 70% royalty? I am unable to make the decision. You can ask me any question you want. I want to benefit from your experience. I will keep its price under 3$ in the beginning. Then, I will see the result. But should I choose 35% or 70% for 3$ price?
For an ebook, if you price your book between $2.99 and $9.99, you can choose 70% royalties. As NotJohn says, this is not difficult! You earn twice as much per sale.
If your ebook price is outside these limits, you have to choose 35% royalties. And note: Any ebook earning 70% royalties has a download fee. The fee is based on the size of your file. If your ebook file is very large, because it includes a lot of pictures, then you might prefer choosing 35% royalties, because there is no download fee. On the final (pricing) page of the metadata when you are setting up your ebook, it will show what your per-book earnings would be at 35% or 70%, so you can choose which one works best for you.
For a print book, royalties are not calculated at 35% or 70%. The author earns 60%, but the book production costs are subtracted from that figure.
I think Mr Abdun-Nafay is talking about scores of photos he hopes are public domain, but probably aren't. Only photos that have actually been released into the public domain, most often through Creative Commons, can safely be used. The exceptions include photographs by US government employees in the pursuit of their work. There may be others, but I can't think of any at the moment. I know a few photographers who watermark their pictures as copyright, but most don't. Yet they are still copyrighted by the photographer unless he or she has actually given up that copyright.
(Don't trust KDP to publish a print edition. Don't trust CreateSpace to publish an ebook.)