After the last post about Yeast Starters, I wanted to look into harvesting yeast again. I did this only once so far, but it can be a good way to save money by maximizing the yeast you do purchase. All it takes is a little bit of knowledge, planning, minimal equipment (mason jars, a kitchen) and time.
The internet can be a good resource. The links below will say it better than I can. The first, I found quickly and gives a good overview of the process.
This video is the one I studied prior to doing this myself, and found it very beneficial, from Beer Geek Nation.
I fully intend to harvest the yeast from my next brew and continue to use it. With proper planning (maintaining sanitation) I can reuse the yeast again and again, ultimately creating my own "House Yeast".
Fear not. Try it!