With Trunks, condition is everything. Over here (UK) you could sell a very smart, clean one for anything between £50 - £150, and the flat top ones do tend to be more desirable as they can be multi-functional. But you are in the States and it does look a little 'tired'. Maybe some others nearer NY could give you some idea on $
Ask of him what you would really like to get for it, then let him beat you down to what you'd be happy to accept.