Real books.
Do you know about FFE's hardcopy prints of the Traveller books? Those are quite real, and are available for not too expensive at all.
As far as I know, they do not publish a "Little black book". They did some reprints long ago, and still have some (I'm assuming legacy) stock. But those aren't the 5x8 books, rather they were 8.5x11 books, 2 pages side by side.
They never were attractive to me, as they looked awkward.
I actually wrote a little program once that took the LBB PDFs, and reorded the pages to be printed in such a way that then printed 2 pages per page, double sided, and then cut in the middle, I would have had LBB 1-3 in a single volume. I was thinking to take that to Kinkos and have them stick a card cover on it and spiral bind it.
Make 2 volumes: 1-4 and 5-8.
Or publish a PDF to a "print on demand" company that can make something like that.
You can get a "perfect bind" printing on line for about $25.
I'm not a big fan of perfect bind printing for something like this, though. It's fine for reading, but not for laying flat on the table. The 5x8 format is too small to make it work, unless you can do it like O'Reilly used to do for its books. Those seemed to have a more flexible back.