The best looking armor coatings and cosmetics in game at the moment are strictly locked behind armor cores. 343 is charging $14.95 for these HCS armor cores and you can’t even keep the armor coating or use the emblem for your weapon cosmetic after the purchase. This is outright injustice, especially considering how bad the armor coatings are. You can’t even use your armor coatings you’ve unlocked on all Spartan models. They are strictly locked behind one model which makes no sense.
I made a post outlining my experience with this as well. Completely unclear and results in non-refundable loss.