That makes me wonder... Those conversions are obviously nice and quite accurate, but the price tarrif is apparently going to be in the range of buying a complete rifle of mid tier price. Thus I wonder if, for true indoor use, it wouldn't be possible to have an East Asian company manufacture some type of Airsoft upper and do the barrel in a bright color so as to mark it as a "training" weapon. Even if made of light ABS, it could still be weighted. Obviously there'd be an issue with accuracy not being great, but I'd think that it could then be used to run some drills and practices that a "real" air rifle wouldn't work as well for.
Shrug. Just a thought. Given ammo prices and such, even the pictured unit may soon be tempting.