Fame
There aren't any rare book dealers who are what we'd call "a household name." Unless it's a household full of book hoarders—er, we mean collectors. But while dealing in rare books won't land you on the cover of GQ, you can gain a lot respect and notoriety in your field.
To gain that notoriety, you could, for example, be the dealer who can always lay his or her hands on stuff that's hard to find. The more rare your inventory, the better you'll be known and respected in the book-collecting world. Also, make sure you always cut people a square deal. Word gets around fast in niche worlds, and if you go around ripping people off, your fame will turn into infamy in no time flat.