i think the Celtics should go for it if he's cheap enough. nothing to lose tbh. Celts might be able to channel his act towards opposition.
I can't imagine what they'd ask for him.
Wolves got a pick and two young role players for Isiah Rider in a very similar situation.
But Cousins is a center so the price would likely be much higher.
Avery Bradley, JaJuan Johnson and all the picks they got? Probably not enough.