I have made many a sourdough starter and find them easy to make and feed.
Ever wonder why sourdough from, say, Boston, would taste different than sourdough from San Francisco? Sourdough gets its name fro the sour flavor of the wild yeast strains in the starter. Commercial yeast isn't as hardy as is wild yeast. When the PH level reaches a certain level of acidity, the commercial yeast can no longer reproduce. The This is also true of wild yeast. However, wild yeast will grow in stronger acids than will commercially produced varieties. It's the acid that gives sourdough its sour flavor. And that's not the whole story. The water in San Francisco tastes different, and has different minerals than the water in Boston, again altering the flavor of the bread.
Sourdough is best made where bread is baked regularly, as there will be more wild yeast in the air. I always made mine in crockery, with nothing more than AP flor, a spoonful of milk 9for the sugar content 0 and enough water to make a flour slurry. I covered the crockery with cheesecloth, and placed it near a screen-covered open window, early summer. This let wild yeast into the slurry while keeping everything else out. my water came from my well.
As the yeast invaded my slurry, it would begin to consume the lactose, and starches, and multiply. I would add another 2 tbs. flou, and water over the next 3 days, once per day. The starter was ready when it smelled yeasty and sour, and was bubbly. After that, it could be used in a poolish, or bigga to make sourdough baked goods. Ass long as you add more flour, and water, it will last forever. Just keep the critters out with a good lid.
Good luck with your sourdough. I have found it best to make in the early summer, when there is wild yeast everywhere in the air.
Seeeeya; Chief Longwond of the North