I wish I’m paying 15¢/kW. At 29¢/kW, it would cost me about $100/year just to run the server. So, the total cost to run your own server at $400 for equipment over 5 years is $180 not $132/year.
Also, why are you paying for 3 computers? Unless you just want to waste money. Why not create a centralized media server to store of all those media and have your other device just access those media over the network?
So, we’re looking at $47.50/year for Backblaze and $180/year to run my own. So, for over 3x more to run my own, why would I do that? Not to mention if I’m unlucky and my hard drive die prematurely (more frequently than normal).