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Yeah Ukraine is basically becoming NATO's dumping ground for their outdated equipment so they can get new state-of-the-art tech themselves.
It's convenient that NATO's outdated equipment is still better than Russia's current equipment though.
Russia makes the bet that Iran can produce drones faster than NATO can produce anti-air missiles. >

Honestly I think they’ll be able to do it cheaper with high volume computer assisted machine gun fire or computer guided anti drone electronic warfare weapons. 
Missiles are expensive but a tracked weapon that either doesn’t need reloading or costs a fraction of a missile is coming. >

cheapest is to kill the source, just need some long range, accurate missiles >

And most effective - I’d go for this option >

Just here to casually remind people that this naval anti-missile system called ‘goalkeeper’ exists.
And while it’d be very expensive to buy even just a few to use in major population centres, Ukraine effectively has a blank cheque from the entire planet to make sure that Russia stays behind its borders. 
But rockets are probably a better option in general. It means militaries who support Ukraine can use this opportunity to donate their ageing stock and replenish with brand-new munitions.