Due to an ever increasing request for 4 color covers, we have been able to arrange a very economical machine-sewn, fully illustrated four-color binding, as well as an library approved adhesive method. In many instances, these are more economical than traditional books with color dust covers. 

Lots of books that have dust jackets are rather plain underneath with a binding band along the spine.  One way to have this band and still save money is to forgo the dust covers in favor of a 4-color cover.  The spine can still have the same banded look along with most, if not all, of your original dust cover layout thoughts.