Another option is book head and tail bands

Book head and tail bands.
Book head and tail bands are the little pieces of colored fabric that we find on on the top and bottom of a hardcover book spine. They cannot be part of soft cover books. The bands come in quite a few solid colors and two colors on a band.
Head and tail bands are strictly for ornamentation but we see them on most hardcover books with professional quality binding. Star Print Brokers includes H&T bands in all hardcover quotes. See both SPB gallery pages for examples. The gallery also shows a book with three sewn-in ribbon markers. So, removing the bands from the quote will not change the cost at all unless you have a quote for a very high quantity.
Coordination with ribbon markers
If a sewn-in ribbon marker is desired, the color should coordinate with the bands. Notice that the book on the left has a square spine. The book on the opposite page has a round spine.
View the gray and white head and tail bands in the center of the image at the top of this post. This example book shows a cloth cover with a dust jacket. It is a hardcover book with a square-back binding. The image on the left shows a stack of books with the bands. So then, the other image on the right shows a few other H&T examples.
In conclusion, know that the bands and ribbon markers are not typical with most print-on-demand services.