I think the best souvenir is one made by local artists. I visit galleries across the world to find one-of-a-kind housewares and decor that use local techniques, but are not kitschy - they have an artistic point of view. At home, these finds decorate my walls and shelves - bringing the places I visited home with me.
In a recent trip to Sardinia, I visited the Tessart Cogoni shop. Unique ceramics made in Sardinia spotted the shelves and handmade rugs and textiles hung on the walls. I purchased a piece of pottery that was the same color as the turquoise water and made with a pasta maker.
For each purchase, Gigi the owner makes sure you know the story of what you are buying. If it's ceramic, it will come from one of two places on the island. If it's a textile, someone in his family has designed or made it.