I've been actively pursuing rare Bibles since 1989. I got the "collecting bug" when I purchased my first Bible--a 1589 "Geneva" Bible for $500. Since then, I have tracked down over 1,000 rare Bibles. Many of these Bibles and Prayer Books have belonged to famous historical figures, including: J. R. R. Tolkien, Captain Bligh (Mutiny on the Bounty), Joseph Smith, Marie Antoinette, Louis XV, Pope Pius VII and Napoleon. The most frequently asked question is, "How do you know this Bible belonged to a particular person?" Well, that's a good question. The "provenance" of a Bible is very important--it is the history of ownership. This can be a combination of the any or all of the following: ownership inscriptions, signatures, auction records, written documentation and armorial bindings.
Here's a recent article about my treasure hunting: https://www.lds.org/church/news/bible-detective-collects-old-bibles-and-rare-mormon-books?lang=eng