player shop limits

Hope i can word this right. But when looking to sell to player shops a big problem is what they want to buy and how many they can actually buy. example a shop will put in marketplace they want 1000 carrots when selling you have to sell a few at a time to find the shop limit. If the shop wants 1000 but can only hold 40 if the market would read 1000/40 to reflect how many they wanted and how many they can actually buy at the moment would make selling a lot quicker. It takes a long time to sell with just selling one or two until you reach the cap of that shop