That's a good idea about the sourdough. I was thinking about trying to find a starter the other day. When I went to the store a couple weeks ago I did buy a dozen packets of yeast, though. So we'll be good for a while on the bread front
You can make your own starter. It just takes time so get some yeast and get started making bread now. Also start growing your starter now and it will be ready in 10 days or so.
You can also reserve a portion of the dough you make with yeast as "old dough". That also become a starter.
Breads made with sourdough, old doughs, preferments, etc. require more time in the rising phase but develop great flavor in return.