These and others are the big chains. Quality Books, Bookazine, Herveys, Pipeline. These are the wholesalers. These are friends of the self-publisher. They are always very helpful.
Contact is the key.
Securing as many quotes as you can from printers once you have decided on the number of copies, trim size, number of illustrations, cover and text ink colors, print run, number of pages, etc. Choosing a name for your publishing company. Securing an ISBN for the book. Usually, the ISBN agency will send you a block of ten, hundred or a thousand. The above are some of the things you should be doing if you wish to self-publish a finished manuscript.