The fam does pyro and the designated license-older is currently super-stoked by his DJI so I looked into this.
You can rent them from Intel. They come in at about $500 per drone per show so you're looking at a half million dollar show, give or take. Fifteen minutes of bitchin' fireworks would likely come in between $30k and $60k so there's a premium, to be sure, but the drones also do cooler stuff and aren't the environmental apocalypse that a Ryder truck full of black powder and phosphorus is.
You can also buy the damn things. Presume this isn't an Intel show, you're looking at maybe $250k worth of gack to make it go. BUT WAIT YOO JUS SED IT WAS HALF A MILLION TO RENT Yeah but now you have to program it and also charge, flight-check, deploy, collect and charge a thousand drones which... well, I reckon it takes a village.