Where do you buy things for your secret base in Pokemon sapphire?

In the Slateport City Marketplace for dolls, mats, and ordemants. In Fortree City for desks and chairs. In the 5th floor of the Lilycove Dept. Store for other dolls, mats, and cusions. Outside Petalburg woods, you can buy plants (the shop that gave you Wailmer Pale)