If he's "very unique" then, by definition, he is not easily replaceable.
Of course there is a limit to how much we should pay him, long term. I'm not saying he's a franchise piece and we should move heaven and earth to keep him. He will literally be making his qualifying offer this season. Maybe $200-300k more? This discussion was centered around your desire to sign Brass and your apathy towards the ramifications that would have for Lemieux. Once he hits UFA status, we can debate how much money we can reasonably spend on a player of his caliber. In the mean time, he's a part of the core and Derick Brassard isn't going to jeopardize that.