Product Option Modification

Hi. I'm looking for a developer to make some modifications to the product options.

I have a customer that wants to offer a mixed case of products. I looked at product options, but it doesn't quite do what I want. I need a customization of product options where we can select the product from a drop-down, then enter the # of items per case and enter an additional dollar amount to determine the price.

So, if a product is $260.00, we would divide by 10 and add $2.00. So the price for the option would be $28.00. I also need the options required (in this case, there would be 10 options and each one must be selected).

I hope this makes sense. We just want a simple formula that can be applied without having to manually change stuff every time a price changes. Please let me know if you are interested or have any questions. Thank you!