Vaulternative Fashion

To make this very simple: Buy the piece you need from Mythressa, upgrade it once for Normal set, twice for Heroic set. Then put it in catalyst.

As per a March 21st bluepost here https://us.forums.blizzard.com/en/wow/t/class-set-acquisition-retrospective-changes-in-101/1549421/101

Something we’re working on is making it so once a new Season begins, items from previous Seasons (so currently Shadowlands s3+4/Dragonflight Season 1) have no currency or charge cost whatsoever. This is to help people interested in hunting appearances and such that they wouldn’t be able to get otherwise.

So I think a safe bet is to collect a full set of the 385 BoA primalist set tokens and hope the change goes live in 10.1.

With the catalyst unlocked it's time to start working towards this. Most people will probably want to shoot for the "Normal" set, since you can catalyze the purple gear from the Primal Storm vendor in Valdrakken to help you get there. Of course you can also catalyze gear from raid and m+ if you've got it.

I confirmed today that a 398 ilevel legs I had lying around catalyzed to the "Normal" set. If others could post their results, maybe we can figure out the min ilevel and max ilevel that counts for normal.

If you want to collect multiple versions of this appearance, it should be possible to get a low-level piece from m+, catalyze it, and then upgrade with valor repeatedly, unlocking appearances as you go.

edit: 395 also works for normal.
edit edit: 392 also works as normal