What Geo said.
$450 is insane.
A/C supply houses sell a spray that is designed for air conditioning coils. Spray it on, rinse it off. I don’t know how a roof A/C is set up but I suspect you might have a little difficult time getting at the coils since they are isolated from the outside, but once you get at them limit your flushing flow of water to less than the drain pan water drain can handle. That’s the coil that is going to be covered potentially with mold, lint, etc. The condenser coil will possibly be dusty but not moldy.