Gingerbread house furniture is not an item to buy - it's an item to make!
Most of the furniture in gingerbread houses is made of a combination of fondant, candy, and (here in Pennsylvania) pretzels! There are books in craft stores for dollhouse sized furniture patterns which can be copied in thin gingerbread that is baked at a lower temperature longer to completely dry out the piece. Royal icing dried on waxed paper can be used to create wrought iron chairs and tables. Small stick pretzels can be used as legs for the furniture. Large gumballs can be used for lamp bases, and large gumdrops with the tops cut off make shades for them. Starburst candy is great to be sliced for books (lots of colors!)or seat and backs for chairs. Small snack cookies make great tabletops.
I have built houses for 32 years - with only one that didn't win in a competition. Have fun with this!