The condition of any game could make its value higher or lower by 50% or more. There is no right or wrong price. Some people want a shopped machine with no problems and are willing to pay for it. Others would like to shop and repair a game themselves and pay far less.
There is no price that is wrong. If it is too high, just move on to the next one for sale. Nobody has the right to say that someone is charging too much. If the price is too high, that seller will eventually lower the price to where it should be, or just not sell it at all.