Each bouquiniste is given four boxes, all the same size paying rent for the stone walls they are attached to--usually about 100 euro a year. Only one box out of the four is allowed to sell items other than books but I venture to guess that has changed significantly. Items often times are set up on the sidewalk in front of the boxes, obscuring all the literary gemstones displayed behind. Currently, there are 250 of these established sellers with an eight year waiting list for the honor of renting the esteemed green boxes.
Today if you pass by these precursors to our current mega-booksellers (B & N, Borders, Amazon...) you will see the toll modern technology has taken on these age old vendors: tchotkies. You know, those annoying key chains with Eiffel Towers or magnets in the shape of the Arc de Triomphe. Little odds and ends that in a mad rush to bring things home for family and friends you will quickly buy and say, "I bought these from the bouquinistes", and it will sound so French.
Actually, these items are evidence of a bigger problem: vendors struggling to survive in a world where antique books and etchings can be purchased for less online. They find themselves having to make ends meet by hawking garish scenic oil paintings or postcards in order to pay their bills. City hall, alarmed by the fact that these knick-knacks are tarnishing the "cultural landscape" along the Seine have invited the bouquinistes to crisis talks in order to promote more intellectual merchandise. The booksellers are divided even amongst themselves as many have remained true to their heritage; filling their stalls with first edition works by Jules Verne, vintage graphics or widely popular comics. Sellers in the more touristy area of Saint Michel have certainly turned to the tchotkie trade, almost to the exclusion of books. It does indeed change the tone of this long standing Parisian tradition.
Time will tell what direction this all will take. It would be sad to see this part of Paris dissolve into a cheap marketing scheme aimed at tourist's whims for what really isn't French at all. Rather, as a tourist, bring home one of those old manuscripts. Even if you can't read it, you will own a part of history instead of a statue made in China.