Can't get yeast or a sourdough starter kit? You can make your own!
Using just unbleached flour and untreated, warm water in a clean jar. I used half white and half whole wheat (whole wheat has more of the things yeast likes to eat). Mix well. The consistency should be a very thick batter. cover loosely (I just set the disc portion of the mason lid on this jar - no ring). Let set for 24 hours in a place out of direct sunlight and drafts. My home temp is about 68F and it still grew. After 24 hours add little more unbleached flour and untreated water. By the next day mine looked like this (picture below). After this stage, take a couple large spoonfuls out each day and replace with more flour and water (equal parts of each) and mix well. You can use the removed amounts to make a small pancake or frybread snack. If you want to strengthen the yeast faster, you can do an additional feeding in the evening - don't remove any for this feeding, just add a little more flour and water and mix well. By the end of day 7, your yeast should be strong enough to make bread. Use a recipe specific to sourdough starters since the yeast behaves differently than commercial yeast.
Here is the first loaf I made. This is 14 days after I began the starter process. I could have made it earlier, after about 7 days, but this is when I had enough time to go through the bread making process.
I used the fold method versus the knead method. It adds gluten structure and lots of air pockets for a lighter, fluffy bread. Getting the dough ready for baking takes a bit of time, but most of that time I was gardening, cleaning my house, walking my dog, sleeping - because it's basically just waiting until the dough is ready for the next step.