Vellum's pricing is a bit quirky: The app itself is free, as is preparing any number of ebooks, but to actually export a book to the various ebook formats, you must pay a fee: $50 to export one book, $100 to export three, or $150 to export five. Those are individual books, not exported files: The export license is tied to a particular book file, so you can export as many versions of a single prepared book as you like. (The downside to this approach is that the title, subtitle, and author of the book are locked after the first export, so you'd better make sure you get them right the first time.)
Whether Vellum's export price is worth it depends on how much you value ease of use and the look of your work. It's possible, with many hours' worth of work by you or a contractor, to style an ebook similarly by hand-coding HTML or CSS, but re-exporting revised text into that styling can prove difficult. Likewise, you can export an ebook from manuscript software such as Scrivener, but the interface is clunky, it requires a separate export for each ebook format, and you'll often find problems or embedded errors.
180g hopes to compel writers and novice ebook producers to uses Vellum by removing those complications and making the process as simple as clicking a few buttons. On behalf of ebook readers everywhere, I hope the company succeeds.
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