If you ever read about the Alaskan gold rush, you will notice the stories about people and their starters. The guys would take better care of their sourdough than themselves sometimes because it provided sustenance.
At various times, I've had a starter but I've never been able to keep it going for years due to moving around so much and not being in one place.
I've learned to make sourdough bread without using additional yeast as so many modern recipes call for. I got my current starter from Cultures for Health. It came dried and it was easy to reconstitute. For those people who cannot eat gluten, they sell a form of sourdough starter for gluten free flours. I have it but have not started using it.
I've been making either bread or pizza most weekends since August. I just make a bit extra starter and let it perk over night. Pour it off into a plastic bowl (do not use metal or it might start eating it) add water, flour, and salt until its like a very thick waffle mix and I let it rest again till its risen. I add enough flour to make it into a dough and let it rise again.
I roll it out onto a floured board, knead the dough and either roll it out to put in the pizza pan or put it in a bread pan. Let it rise till its ready. Put toppings on it if its a pizza or let double if bread and bake till done. I'm sorry my instructions are not more specific but I go with the feel.
The other week, I read about a apple walnut cinnamon bread recipe that sounded good. I followed the directions and used the sourdough instead and it turned out really well. I loved it but I need to make a couple changes. One is cutting back on the filling and the other is rolling the filling into the dough instead of cutting the dough into pieces.
When I'm not using the dough, I stick it in the refrigerator to slow down the process because I can't use it every day. I downloaded the e-book on using sourdough from Cultures for Health so I'd have a ton of recipes including a peanut butter sourdough cookie one. The e-book was free and I need to sit down and explore it so I can try a variety of recipes.
You don't have to buy a starter, you can rely on what ever is floating in the atmosphere by setting out an equal mix of flour and water for several days until it is nice and bubbly. I'm off to work on my sourdough pizza for tonight. Check it out or if you have any questions, feel free to ask.