Missiles expend all of their thrust on accelerating/climbing and very little in sustaining flight. However, missiles like the RIM-7 Sea Sparrow for example, had a bimodal rocket motor that had a high thrust on launch & a lower sustaining thrust at combat speed.
This is true, so fitting a MANPADS to an aircraft and launching it in forward flight at the same altitude as the target a missile like Stinger or Mistral or Igla or Verba will become much more powerful and effective as an air to air missile than they would as a MANPAD fired from the ground.
With a ground launch a MANPAD would not be much use against a drone flying at 10,000m, but get into a light plane or even a not light plane like an Su-25 jet it cold climb up to the altitude the target is operating at so the missile can use all its fuel to accelerate and chase the drone target, which means it should easily kill the target because it does not have to climb 10km to reach it and can be fired from a closer range too.
A MANPAD missile is much cheaper than most AAMs and also much lighter so you can afford to use 10K missiles against a 1-2 million dollar Turkish drone, as opposed to firing a million dollar long range AMRAAM missile from an F-35 that costs 70K per hour to operate.
Firing a more expensive air to air missile like Sparrow or Amraam.... it would probably be cheaper to use a medium range SAM like SA-6 or SA-11 missiles from old stocks to use them up before they expire.
Having a cheap light plane and a cheap light missile is the important part of dealing with drones which the enemy might have in large numbers.
Even an igla is close to half million$ per pop?
From the SIPRI international trade register:
India ordered Igla-s Portable SAMs in 2008. They were delivered from 2008 to 2012. The order was for 250 missiles and 250 missiles were delivered.
It was a 26 million dollar deal.
250 missiles for 26 million dollars makes the cost per missile in this instance... about $104K each.
Of course there is an earlier deal for Igla missiles from 2001, that were delivered from 2001 to 2003, this is the shoulder fired missile and the deal was for 50 million dollars for 2,250 missiles... this missile does not have the proximity fuse for dealing with very small targets but would be fine in an air launched model for shooting down drones like the Turkish ones from an aircraft and it works out at $22K per missile which would be quite reasonable I would think.
More recently India has ordered a lot of Igla-S missiles and they will probably cost more than 104K each but that is because they are making them in India so you have to build a factory...