Is $700 to repair a ceiling drywall spot a fair price?

My tub apparently needed to be caulked, and my toddler decided to put her bath water out of the tub, causing the damage. The damage is on the living room ceiling. I asked about prep work and painting; I was told that since it's just basic white paint, they may not need to paint the whole ceiling, but they will if needed. I think the reason I was asked to pick up the drywall was to save me some money, but Lowe's had the drywall for like $20 a piece. I'm also a bit confused and wonder if it doesn't need to be replaced, as I'd rather do another option if possible.