Possible cost of replacing kitchen ceiling?

Hello all, I'm currently living in my sister's house and have been repairing existing issues in the house one by one...thankfully with the help of my sister. The last major project is the kitchen ceiling. A few years back, due to the issues in the bathroom such as various leaks, it has left stains in the ceiling among other things and the kitchen needs to be replaced. I had one guy come out to take a look at it and he said that he would email me an estimate tomorrow. I have two more guys coming out to give me an estimate. The guy that came today said that I would need at least 3 5x8 sheets of drywall. I can't get in touch my family friend who does this kind of work that I can't seem to get a hold of who I know would give me a great price and do an AMAZING job. I just want to know if there's anyone who knows what the average cost would be just so that I'm not getting charged a ridiculous amount of money. My kitchen is really small.