I am not in favor of selling Oscars unless I know the buyer has the correct equipment to look after them properly. Big Fish are often difficult to get rid of because of this very reason. My advice would be to take them to an aquatic shop and see if they will take them off your hands. Unfortunately, they may either offer you very little money, or take them if you actually give them to them.
If you are not able to give the Oscars a suitable home, then please do your best to find a home for them, even if it means you not actually getting any money. I have often read items large fish [not Oscars] and I've had to give them away.