Very simple DIY ATO solution and with some searching you could probably find cheaper options. I just put what came up first.
https://www.amazon.com/GEREE-24V-38...UTF8&qid=1512345974&sr=1-6&keywords=ssr+relay
https://www.amazon.com/gp/product/B00Q2E5IXW/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/uxcell-Water...8&qid=1512346008&sr=1-22&keywords=project+box
https://www.amazon.com/gp/product/B00FHAEBIA/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
https://www.amazon.com/SlimLine-224...qid=1512346153&sr=8-3&keywords=extension+cord
I’m new to this ato and not very knowledgeable with electricity. Could you elaborate more on the diagram or pm me! Why is there 2 float switches in the diagram?