I had never heard of these critters until your post.
I came across
this page on them (google to the rescue).
The one paragraph says
Properly known as pseudoscorpions, these tiny, tiny creatures have a fondness for old books, because old books also happen to contain delicious booklice and dust mites. And they’re really not book scorpions… at all because they can’t hurt us, and they’ve basically been performing a free pest control service since humans started stacking excessive numbers of dusty, bound-together piles of paper along our walls and nightstands. This arrangement works because old book-makers used to bind books using a starch-based glue that booklice and dust mites love, so without a healthy population of book scorpions patrolling your collection, those gross parasites are probably having a horrible, silent field-day chewing them all apart.
So I'm thinking, look around in used bookstores for old, worthless books? Or maybe your local library might have some oldies you can buy. Possibly you can attract some that way, or maybe the books will have them already.