I have a shopping cart with items that decrease in price as you add or buy more items. However, the problem is the user can only see the price drop AFTER new items are added.
Do you have any ideas or have you seen examples of carts or interfaces showing a future state based on potential selections?
For example, a cart showing the price drop BEFORE the hypothetical new item is added.
In essence, you would like to encourage people to purchase more by illustrating potential rewards.
In general, the case with all e-commerce websites is that the main focus is always given to the product. Since you wish make potential rewards your main focus, you can provide an icon towards the bottom right of the product, where on hover, the user will be able to see current cart amount plus the potential benefit either in % reduction or comparison between otherwise amount & benefit amount.
Below is an illustration of the concept. Your product listing is same as traditional e-commerce website but benefits are communicated via a strong colored icon. This concept is for product list page where space is always limited. On the actual product page, you can try different iteration of this concept. I hope it helps.
Volume discounts are all about incentivizing bigger purchases. Relying on people to discover those incentives is rarely effective.
Just spell it out ...
download bmml source – Wireframes created with Balsamiq Mockups
You could implement a button somewhere around the "Buy" button of each item and call it something like "Click to see what you're saving by adding this item". The user then can click on it and it will show a quick dialogue where you simulate what would happen to the prices of the items already in the cart if they added this item.
