Of course they'll try to get it from you for free, ridiclious. Well since
But if you're really not using it, and dont care about it just sell it 100$ and I think they'll give it to you without any question.
However I dont know which offer are you really thinking about. But I guess you could get even up to 1000+ from them, just dont set it up to high. If it's too high and they threaten you to take you to the court, still deny them, low the price a bit and finish up.
If they call you again, complaining how the price is too high and that they'll really take you to the court this time just accept their offer, cuz this time they will take you to the court.
IF you really care about this domain, then just offer them your price, not reasonable take it to the court.