Would it be possible to add a button to the commodity screen titled “Buy Max”? It would purchase the maximum amount of commodities either available, that you can afford or have the storage space for.
You have 240 units of space, there are 196 widgets available, and you have enough cash to afford them, it would buy 190 widgets with a single click.
You have 240 units of space, there are 255 widgets available, but you only have enough cash for 160 of them. Again, 1 click would purchase 160.
You have 240 units of space, there are 255 widgets available, and pleanty of cash on hand. 1 click would purchase 240 widgets.