Actually, he did make a specific claim:
The claim is so wild that I’m asking for a cite.
The argument is absurd and perhaps there is confusion between machine guns and bullets (which are damn cheap as these things go) and things such as Patriot missiles, which are expensive as hell and can cost far more than a drone.
Presumably, the cost of the radar and targeting system cost far more than the machine guns.
@gnoitall gave a good overview. It’s worth reading again. As gnoitall says:
The only point I disagree with is:
It seems that the majority of attacks on oil facilities are being done by the An-196 Liutyi (Lyutyi) drone, and googling the costs show a wide range from $55,000 to $200,000 per unit. At any rate, it’s not the $500 to $1500 drones that are being targeted here.