The typical price for a business that had drop ceilings and drywall is $150-$300 depending on number of drops ordered. A single drop is barely worth the materials to deploy a tech.
Using that understanding doing it in a house will easily add $250 for the headaches that can happen. So knowing it is $300 and then a possible $250. $900 seems reasonable in the aspect of they have to make money and they have to make sure that sending the tech is worth doing. She got a quote that was the “I don’t want to take this job” price.
Think about it like this. If you were to tell me that you would pay me $50 to come make you a pot of coffee plus all of my travel and materials. That job to me is not worth it. However if you told me you would pay me $500 plus travel and materials. That job becomes worth doing.
You cannot have much time in this or you likely have only ever worked on type of install. $120/drop is the price you charge for simple installs that have zero complication. Just wait until you see fire blocking, runs that go over really weird sections of building, etc.
Ask any veteran of this business and they will laugh you out of the room.