Here are several links I have found for simple 18" doll clothing, doll furniture and accessories. They are all free and very doable!
Furniture; Bunk beds; farmhouse bed; mattress; pillow and much much more.
backpack-could be made larger for an 18" doll
This site is loaded with clothing and lots of accessories including furniture, etc.
Seems to me like more and more sites are becoming available for us DIY selfers.