Alien Mage Set

Why is people begging for my purple alien mage armor (chestpiece)

Yeah, I'm back. Back playing dungeon quest. (Not) Back in the wiki. Anyway, I need (preferably purple) alien mage armour. I've got a maxed inventor's greatsword but I don't know if that's a good trade. Just tell me what is a good trade for alien mage armour in the comments.

Me: grey alien mage, grey alien warrior and one green piece alien guard

Them: non upgraded purple guardian glorious chest

What is the most (quantity/highest lvl of a legendary weapon) I can get for trading my Purple Alien Mage Armor and Blue Alien Mage Helmet?

I'm expanding my leg collection so I would like to maximize the value of my Alien Mage Set in trading

Getting 3 alien gear in a row