LUK robes aren't worth so much actually. Basically, the only people who demand them are low-level Magicians trying to get enough LUK for some other equip. I was actually in that position a few days ago but ended up scrolling my own robe. It's hard to tell the price, as demand is low. Maybe 20M, based on what I had been ready to pay
Some might do that, and especially so if they intend to stay DEXless forever. But most thieves want to equip LV100 or 110 weapons, which require DEX. Therefore there's higher demand on robes scrolled with DEX
