I understand what other forum members are saying about the cost of furniture items in Spain. Please bear in mind that much of the information comes from expats who bought before brexit. Things have changed. Potentially you will have to pay to import goods now, thereby making them less attractive pricewise.
Spain has IKEA, DFS, leroy merlin, marks&Spencer and amazon.es as well as a host of local furniture shops. You can also source stuff from the likes of Westwing, manomano, kave. With Google searches there's a host of companies.
Hope this helps regards Karen