I bough the "Put it On" feat (for completing the Dystopian Amazon style set) over on another character, so I could get the discounted price for the in-game currency I had. Detective McNulty (the Metal Part 1 vendor) is still selling them at full price. So I switch to the character I originally got the feat on, and even on that character, he was still selling the purple gear boxes at full price. I checked with the Thanagarian vendor, and he's selling the Battle-Hawk boxes at the discounted price if the "Ad Hawk" feat is completed. So it seems to just be an issue with the Metal Part 1 vendor.
Purple gear styles do not give a discount for purple gear. The elite style feat gives a discount for elite gear and regular vendor gear, the regular vendor style feat just gives a discount for regular gear. Edit: I could totally be wrong because I have both style feats and don't see a discount for Dystopian Amazon gear either.
If you check the JLD and Metal 1 Vendors, you'll find that having the purple style feats does give you a discount on the boxes (as the feat descriptors themselves say). It's just the Metal 2 Vendor that isn't giving the discount as of my posting of this thread. Hopefully it gets fixed, as I want to get the styles on one of my much lower level alternates with what few Dark Metal Coins I got on said character while Metal 1 had Event Mode.