I had a neighbor who made Mandolins. He had a source for some very nice stuca Spruce. It was near San Francisco. I tried to talk him out of a board, but he wouldn't part with what he had, but promised to pick me up one on his next trip "in a few weeks". Well then next I knew, the moving van was taking him and his wood away. And he never told me his source.
Bass wood is a good substitute. They use it in window shutters.I had a ton of wood shutters in my house. As we removed them, I stripped the larger pieces of wood from them. After being in the sun for 12 years, they were nice and dry, and light. I built a number of wings using wood ripped from them and they were very strong and no heaver than a balsa wing. I replaced a broken wing on an ARF I had and the replacement weighed less than the original wing. Look at a cabinet shop or shutter shop. You may be able to talk them out of some wood.