You're on the right track but comparing the wrong things. It's cost of the rounds vs the cost of not stopping the incoming weapon (ie lives and damages), not vs the cost of the incoming weapon.
Last time I looked in to it I'd still need a supplemental heater for when it's too cold for the heat pump to be effective (there were a handful of weeks just this/last year where we would be in trouble) in Chicago.
Ground source makes a lot more sense for new construction where you're already digging.
Got a pair of devices a bit like the halo to keep in the cars going forward. Car went in the shop a few days later for something unrelated but they tested the battery and there was nothing wrong with it, the engine was just too cold.
There's unfortunately no trick to bringing home full 4x8 sheets which is generally what I need. And the rental is too much hassle, especially for small quantities. You need somewhere to park a 4x8 trailer, they're not small.
It's much more time consuming and problem prone. I've lived this way for years now and want to be able to just drive out and haul shit without the hassle. This shit is a hobby and the rental nonsense makes it feel like work.
Who said anything about contractors? I'm currently watching the ev truck market because I diy a lot of shit and hate having to rent a truck to buy plywood. These aren't for contractors.
It's the cornerstone of their methloften line.