To be honest, from the Palace ST holder I work with, it seems that Zaha is basically really dim.
He thinks Zaha doesnt really see a distinction between CL and EL, "so long as its europe". And that he is very easily lead by agents etc.
I would suggest, his apparent desperation to join Arsenal, supports this.
That being said I do agree, if he is available at £50m we should certainly get in on that.
Although honestly I think there is a 0.01% chance of Parish accepting an offer so low, particularly when he has already banked big money this season - could he afford to sell both crown jewels? And because he would have to pay a quarter over to Utd.