When Notch & Salt registered a block of 100 ISBNs through Bowker, the reasonable question was: why would a small press need a hundred of anything?
The arithmetic answers most of it. An ISBN identifies one format of one title — not one book. A single novel published properly across formats eats numbers fast: paperback, hardcover, and an ebook edition for wide distribution each want their own. Call it three to four per title. A fifteen-title catalog is instantly fifty-plus ISBNs, before a single revised edition, boxed set, or audio release. Bought one at a time, ISBNs are punishingly priced; bought in a block of 100, the per-unit cost collapses. The block isn't ambition — it's just buying wholesale for a shelf you already intend to fill.
The strategic half matters more. When you buy your own block, your imprint is the publisher of record in every industry database — Books in Print, library systems, wholesale catalogs. Use a free ISBN from a platform and that platform is listed as your publisher; your catalog is scattered under other people's names. With the block, every Notch & Salt title, on every platform — Amazon KDP, IngramSpark for bookstores and libraries, Draft2Digital for Apple, Kobo, and B&N — traces back to one press. That consistency is what makes an imprint an imprint instead of a pile of uploads.
And there's a quieter signal in it. A hundred numbers is a commitment device. It prices in the next decade of books, which changes how you make the first one.