I've slowly been getting all the armour sets, it's the biggest grind. The annoying thing is that I have already gotten the armory trophy when I was crafting the different helmet sets for the Hardmode ore. So at one point I have had every armour piece in my inventory I have just sold them.
The hardest part is getting the armour pieces from enemies like the shadowscal armour for example.
I have resorted to farming oysters for luck potions.
by Jordan_Feather