I'm what people call a "craigslist whore." I'm constantly buying and selling.
Now, those seats look like they are from a rather new truck, did he say what year? That will be the deciding factor in whether he sells them or not. You have to keep in mind, alot of people with new trucks are rather wealthy, and will normally buy parts straight from Ford. Another thing you have to consider is location. Is he located around some body shops or repair stations? They also will be willing to pay more for the exact part, because those seats from Ford will probably run around $1000 for both, and then 100 for the center console. Tracks may also be extra.
He will most likely get CLOSE to his asking price. You'd be amazed.
I'm not saying that ALL seats are worth $400, I have a pair right now I'm selling for $20 or free to a TRS member. I paid around $40 for my Explorer seats at the JY, but I would be able to sell them for between $200-300.