Disecting this solution
There is a program called T-Works Manager, (you can download the demo from the website). They basically have a pricing matrix feature where you can create a new matrix and have the prices determined by the number of garments and the number of colors in the design, I have attached a screen shot of the matrix.
Then, on the invoice section, you can select which price table you want to select for each item and the price will be adjusted based on the tables you create.
Can someone help me? I need to create a solution similar to this, I have paid people on freelancer.com, I have done all the lynda.com tutorials, I have purchased filemaker books, and I am still lost... Can someone please point me in the right direction?