No, but you're thinking about it wrong.
Lord to his steward: "OK, here's a purse of 300 gold. Use it to buy food at 30 gold per hundredweight until it's used up. Once it's gone, I authorize you to buy any other food that comes in at 10 gold per hundredweight, out of the treasury, as long as we have less than 1000 food stored."
Does that make more sense?
I was speaking about caravan logic, not warehouse logic.
