is it CHEAPER to buy a SHED or to take the DIY route

Im about to build 5 sheds in my home backyard and compare the price of DIYing it, or buying a prefabricated shed, or to hire a professional contractor to build them for me. I got quotes from contractors, and did comparative pricing on prefab sheds. In the end, I decided to build them myself and Im going to break down for you the cost and timeframe. Templates Concrete mixer: