> Electric resistive heating is much more expensive than gas heating.
That seems like a complex question to answer.
Electric heating is more efficient than gas heating (100% Vs. 95%), but electricity costs more than natural gas, taking out any benefit. But that isn't even what makes this complicated, if they're running their natural gas whole-home system to heat a single room, how does THAT compare to a more costly room heater?
Heat pumps are definitely more efficient (e.g. 300%) but cost $1K for a single mini-split, and installation costs/permitting is expensive. $5K isn't unrealistic for just one installed, maybe $2K~ DIY (assuming you can even pull the permit yourself for both electric and HVAC).
I hear that Mr. Cool is a good DIY heat-pump option. The refrigerant is "precharged" / included (i.e. you don't have to mess with refrigerant). https://mrcool.com/diy-4th-generation/
Maybe a heat pump is more efficient (about the same as gas, depending on climate) but needs more capital than $25.