It's actually not that difficult to create your own starter. All you have to do is harvest a wild yeast, which can easily be done. I got my last one from green grape skins, and it works great.
The key to keeping your starter healthy is feeding it consistently, about once every 2 weeks. Feed it sugar, as that's what allows the yeast to reproduce. Your container should be air sealer, only only be about 1/3 full. As it grows quicker than you will be able to use it, don't be afraid to throw a bunch out to keep the container at the right level.
