With a bulb made of alumina and having a window made of quartz on which thin films have been deposited, it would be more expensive than a traditional incandescent lamp, but that would be compensated by the high efficiency and long life.
If in mass production, I see nothing that would prevent it from being cheaper than a comparable LED lamp.
I am not familiar with the technology used to make the incandescent band made of carbon nanotubes and boron nitride ceramic, but everything else is made with standard equipment that is widely available.
I didn't mention this in my other comment because I thought the use of alumina could be avoided, but I suggest you look up the price of some optical sapphire (ie transparent alumina) before you get excited about that. Even for a tiny, flat circle you're looking at around ten bucks. A bulb would likely be harder.
The alumina used must not be transparent, it must be as white as possible for maximum efficiency, so standard cheap alumina ceramic should be OK.
The light exits the lamp through a flat window, which is made of quartz in the prototype, but in mass production it is likely that some kind of alumosilicate glass or borosilicate glass would be fine for it.
Could it be made with a plastic and not glass exterior? One minor benefit I have enjoyed about the transition to LEDs is that they are physically more sturdy and will survive being dropped.
The alumina cannot be replaced with plastic for 2 reasons.
It must be hermetic, to keep the argon inside and the air outside, for the lifetime of the bulb.
It contributes to the high efficiency, by reflecting both the visible and the infrared light and preventing thus the heat loss from the lamp.
Nonetheless, alumina is less fragile than ordinary glass.
It might be possible to replace the quartz window with some kind of glass window, for a lower cost, but not with any kind of plastic, because it must also be hermetic and it must be usable as a substrate for thin film deposition in vacuum and it should have a coefficient of thermal expansion matched to those of the multiple layers of the infrared-reflecting filter.
The key innovation here is the IR-selective-reflection bulb coating. As such:
>Fabrication of the VTIRF window
>The quartz substrate with a size of 25 mm by 50 mm is cleaned by bath ultrasonication using acetone, ethanol, and deionizing water for 10 min. The Al2O3 and HfO2 layers are deposited by atomic layer deposition (R200, PICOSUN) at 255°C using trimethylaluminum (Strem Chemicals) and tetrakis(dimethylamido)hafnium(IV) (Strem Chemicals) as precursors, respectively. The oxidizing agent is H2O. The precursor carrier gas is N2 (99.999% purity, Shanghai Weichuang Gas). The Ag-Ge alloy and SiO2 layers are deposited by electron beam evaporation (PVD 75, Kurt J. Lesker) in vacuum.
I'm no expert on how LEDs are made, but this coating certainly doesn't assemble itself.
All the layers are deposited successively on a larger glass panel using standard vapor deposition equipment, then the substrate is cut into the individual glass windows for the lamps.
The article mentions explicitly all the equipment that has been used in the fabrication of the prototype.
The fabrication of any semiconductor device, such as LEDs, includes many more such vapor deposition steps done in vacuum, using the same machines, but with much more stringent requirements for cleanliness and defect control.
Any defects in the deposition steps for such a lamp window will just reduce the efficiency of some lamps by a small fraction of a percent, while during LED fabrication they would have made unusable LEDs that would have been dumped.
