As Paris souvenir, you can buy a replica of the Eiffel Tower or a Paris T-Shirt at most tourist sights. We recommend you to buy french fashion, food in Paris and bring them back home.
A quality Paris picturebook is a good Paris souvenir. We recommend the picturebook "Paris seen from the sky" by Yann Arthus Bertrand.
Photographer Yann Arthus Bertrand is known for his pictures of the world from the sky. The text is in French, but the pictures are what matters.
Saveurs du jour: French store online, USA
Eatfrenchfood: French food delivered in UK
French Flavor: French food, UK and Canada
Bernard's wine route: French wines in UK