I'd give him $150-200, the tag adhesive on the cone means it is almost certain he bought used. No telling how much it was beat on when it looks like that.
OP I wouldn't pay a dime over 175 but chances are he will take that as a massive low ball. Unless he is willing to go that low I wouldn't bother with it.
Look for another sub.Why would he be selling it? It looks trashed.I wouldnt touch it.Surround looks like it has a couple holes in in to me,.Just my opinion.