If we're at the point of Thing 2 - actual implementation - then it's a matter of who exactly is going to do the work.
Again, there have been several proposed alternatives in the Thing 1 category. The actual material cost is quite modest. The relays WITH socket are a couple bucks each (no soldering required). Toggle switches with screw-terminals (no soldering required) are about $1. Screw-terminal barrier strips (no soldering requried) are also modestly priced. DC voltage regulator module with digital LED voltmeter are about $2 (no soldering required).
So taking a somewhat cynical view of the matter at hand, the material cost for all the proposed variations/alternatives will be small compared to "labor" even at minimum-wage whatever that is these days!
