Whats a BN?
Off the top of my head some approx prices:
GTR copy front bar: $450
GTR side skirts - keep the gtst ones, theyre better, if you dont have them, budget another $500
GTR read pods - keep the gtst ones or as above fork out another $300
GTR rear spoiler $200 Maybe cheaper, noone wants rear spoilers anymore.
GTR bonnet - $700 plus latches
GTR grill $200
In my opinion if you have the stock side skirts and read pods, just remove the rear spoiler and get a gtr front bar, dont worry about the rest.