A MOAB apparently has the equivalent of 11tons of TNT. A drone carrying a grenade has up to 180 grams. So you need about 61 111 drones to deliver the equivalent explosive. At that point it might be cheaper to just bring the MOAB.

We're talking about bunker-busters - the MOAB is not a bunker buster. It's an airburst weapon designed to clear out large open spaces, and isn't effective against hardened bunkers.

No reasonable amount of quadcopters could match a bunker-buster. Surface explosions are not very effective against buried targets.

The weight and density of the bunker-buster is extremely important to its operation. When dropped from a high altitude, it breaks into the bunker with sheer kinetic force, and then explodes once inside.

Those are entirely different missions. A GBU-43 MOAB is used against soft targets on the ground. A GBU-28 is used against hardened buried targets. It's simply physically impossible to dig a big enough hole with a bunch of small drones or bombs: the only way to penetrate deeply enough is with a hard object moving really fast.

>How many $200 quadcopters delivering blow after blow to reach the equivalent damage to a single <orders of magnitude larger purpose designed munition>?

How long do I have to piss on a steel plate to get the same effect as a waterjet cutter?

About the same answer.