Without knowing the exact conditions of the place
there is no way to say.
Did you have a consultation and get a price estimate before the clean up?
Some small tiny little places have hazardous conditions and that always costs a lot more to have cleaned.
Was there any animals, rodents, insect infestations, human waste or mold?
That always costs more to have properly cleaned and sanitized.

I hired a cleaning service to clean out a small 1 bedroom apartment when I became overwhelmed with cleaning it myself.. I bagged about 30 bags of trash before I decided I needed help,

The company is charging me 4500 to clean up. Do you think this is a fair price or is it too high?