When i went on a crafting spree, I didn't keep 16 million crystals on hand. I got them as I needed them (which I did) and most of the space you would have spent on crystals i needed for the items I was making (red curries) which I was holding until i reached the skill necessary for the HQ tier on red curry buns.

I'm not really a diehard crafter, though this specific thing I've spent a fair amount of time and space with trying to cap cooking.