To calculate sales price of a material

Dear Experts

We have a requirement to find the sales price of each material for a particular material.

The purpose is to create the custom program that should propose the business to tell how many materials

can be sold to a particular customer with the available credit limit.

Hence if anyone worked on this kind of requirement earlier, kindly requesting you to advise me on the processing logic to find out the sales price for a particular material for particular customer.

Eg:Base price(Cond type) :100

Tax (Cond type):10

Sales price :110

As mentioned above, would like to know the processing logic to derive as 110 (Sales price) for a particular material for a customer.

Thank you very much in anticipation.