Quote Originally Posted by illutian View Post
The issue with that is each 'stack' takes up a Retainer "Sell Slot".

And for me, personally, I'm trying to clear out Retainer inventory from 5+ years of playing (read: pack-ratting). So I have many materials with over 300 quantity, but since they're old they don't move. Though, when they do it's for significantly more than the Vendor Sell price.
Maybe you should consider the market and vendor a reasonable stack at a time - you don't have to just flat out sell everything in 99 Stacks, you can sell it in various amounts based on customer need. Have you learned nothing from the Crafter Job Quests in Stormblood?