One of my best uses for home assistant is fine tuning the fridge and freezer temperatures.
At one point the fridge was not cycling and just running the compressors nonstop. I was able to adjust it so it cycles properly and stays within proper temperatures.
I also use it to monitor temperature and humidity inside and outside, cloud patterns, sun set and sun rise times, monitor power use and all my batteries and charge status (off grid). And will keep adding more and more. Hoping to some day monitor my water tanks that will collect rain water soon.
All this and it only consumes maybe 3 watts for all the smart stuff.
Before I moved we used it to have automatic lights in some rooms, and when someone goes in front of the driveway camera all the lights in the house changed color to let us know. That alone was a life saver.
1/2 to 3/4 of my drives are from server parts deals, only had one of them give me issues and I think the issue was the SATA cable I had. I have several servers.
They are used drives, but I only paid about $100-125 each. Keep watching their site and things go in and out of stock all the time. I wait until they have a good price.