Pay for your inventory.

[TitaniaZero]

But why do you need an entire retainer for mats? The only mats I keep around are the rare/expensive ones that aren't easily obtained. Otherwise, I just buy what I need off the MB, craft whatever it is I wanted to craft, and then resell the rest. I don't keep mats precisely because they're a huge waste of inventory space when I can just go buy what I need when I need it.

I generally just go out and gather all the things I need for a crafting project for the day.

Besides the point: What you buy, someone has stores of, ie likely mostly taking up some space in an inventory.