I recently purchase sourdough starter in a silent auction. You can start sourdough on your own just by letting flour and water sit out to absorb whatever wild yeast spores are in the air. We've done that before but we gave up because the flavor wasn't all that impressive. The sourdough starter that I purchased in the silent auction, however, has a delicious smell. It must be pretty resilient too because it is said to be 150 years old!
Today I used it to make a sourdough rye bread. Yum yum yum yummm... Excuse me while I get back to eating the entire loaf.