Yes, it's distasteful and the person who bought the painting at a knock down price was a slimeball taking advantage of desparate people. But, knee-jerk eotions

Yes, it's distasteful and the person who bought the painting at a knock down price was a slimeball taking advantage of desparate people. But, knee-jerk eotions adide, in essence the situation is no different to anyone selling anything at a knock down price when they're desparate for cash. I'm sure a lot of us have been in that situation. But, if you don't like the amount you're being offered, find another buyer. If you can't find another buyer then take what's on offer --or don't sell. Either way, it's not really on to come back years later, complaining you were ripped off and demanding [as ever!] compensation.