i work with IR emitters (LEDs) (similar to this project but with several cameras), in the SWIR range a single LED can easily cost 10-20$. they tend to have very low efficiency at these wavelengths too, typ around 1mW/sr (120 degrees) at 50mA. a good SWIR setup with a camera and led illumination will quickly be 20-50k.
I guess what he is implying is, that the LED is the biggest cost factor on the BOM of such a product. If you have the goal of making such a product available to every household, would it be a feasible product if the bill of materials is say 40 USD already? How much would people pay for such a thing?
Of course in electronics everything gets massively cheaper with scale.
