Lightning Source is the dominant Print-On-Demand company, producing books for publishers of all types and sizes, including my own Silver Sands Books.
Their printing price for standard paperback books is 90 cents, plus $.013 per page. A 300-pager will cost $4.80. Pricing-per-page seems very logical to me, but that's not the way some self-publishing companies work.
Here's the price chart from E-BookTime.com:
Prices are based on page ranges, not the actual number of pages, When you exceed a range by one page, the minimum retail price goes up two bucks, and the author's wholesale price goes up $1.40.
(above) Infinity Publishing's book pricing is strange. Their suggested cover price for a book with 129 pages is a buck more than the price for a book with 128 pages. The author pays 54 cents per book for the additional page. Page number 129 is printed on a very expensive piece of paper. Independent self-publishers who have Lightning Source print their books pay .013 for an additional page. Ironically, Infinity's $149 Extended Distribution Package uses Lightning Source to print the books. Infinity pays Lightning .013 cents (or maybe less) for page number 129, but charges authors 54 cents! That's a nice markup. Infinity also says that its own printing and fulfillment are better than Lightning--but they are willing to use Lightning anyway.
(above) Xlibris also has an inflated and weird "delta" between page ranges. As shown above, a 107-page paperback book will sell for $15.99 and the hardcover will sell for $24.99. If you add just one page more, the price goes up $4 or $5. The difference in the manufacturing cost is tiny, and can't possibly justify the difference in cover price.
The price for a paperback with 398 pages is $19.99 (just like the 108-page book), but, at 400 pages the retail price jumps four bucks to $23.99, and that price holds all the way to 800 pages. Xlibris gives away 400 pages for "free," but charges four or five bucks for one page! Xlibris books are printed by Lightning Source, so the price per additional page is $.013 (or maybe even less if they get a discount).