Adding a second price that is tied to the main price
 

How much customization would be involved in adding a second price? My main price is per thousand, but to actually calculate total pricing I need case pricing (which can be calculated by taking the per thousand pricing, dividing it by 1000, and multiplying it by the number of items per case, which is currently an extra fields value). This price would need to be stored in some sort of global variable that is dynamically created based on the per thousand price and can be accessed and displayed on all pages as well as on the invoice. This is more complicated because I also have wholesale prices that will change both the per thousand price and the case price based on total cost. 8O

Example: Customer orders 1 case, which is 3000 items, with a price per thousand of $10.5 and a case price of $31.5. If they order $100 or more of this product, their price per thousand decreases to $10, which makes the case price $30.

The case price has to be directly tied to the per thousand price for this to work.