Sir, I am in another profession altogether and ethics matter. I do not have your skill set, as I am a boiler inspector for several different power plants, but I'm also a father with a young daughter who just bought her first car. https://bobistheoilguy.com/forums/threads/1st-oil-change-on-daughters.344235/I do recall that. Someone trusting me to work on a vehicle at a professional level & not rip them off is different than me giving someone their ASKING price for a used vehicle that's been sitting for 2 years.....That I can't test drive & could have turned out to be a real turd.
That was a risk on my part as I paid for the car BEFORE I repaired it enough to get it home & still needs a plethora of repairs before I would consider it roadworthy.
IMHO, you did nothing wrong or unethical; congratulations on your score! My question might be....Does your daughter have any understanding of what you just did for her?