I can tell you that from what they paid , their closing cost and what they have put into the house- I can see some of it, they may be very right here. You do not know if they took out a loan for repairs or not, but the house is priced right for what they paid. They are not supposed to pay you to buy the house.
I know what their closing cost will be, except for their loan balance and what you are asking for, and I know what they paid. I have an idea what they have spent and I know how much the home should have appreciated, they are not asking too much for the house is you are figuring this way.