Agree, the person is trying to ask YOU to take it off his hands. That alone cuts the value.
One third of retail would be more than it is worth.
1/4 a little low.
So start adding up retail.. divide by 4. save number. divide retail by 3 ..that is the # not to go over.
Start with the 1/4 of retail offer.
If the seller does not want to sell ar less than 1/3 retail. then tell him to pack it all up. goodbye.