318 air filter box insulation

Upon checking my air filter it was loaded with a black powdery substance.
there is a thin foam lining inside the air box held in by a birdcage like apparatus .both top and bottom .it is completly deteriorating. dealer says foam unavalliable and wants me to buy a new box at $250.00 Any help ideas or foam specifications would be appreciated thanks Bill

what year is it?

Hi it is a 1997 318IC

I have a 95 318ic... i thought they only made them 94-95... but i never had any insulation in my box so it might have been put in from the previous owner but im not sure