Promblem presenting product properly


I have Product A, Product B and Product C that I sell in the same category.

For each of them, I offer 1, 2 or 3 color imprint. (it is always the same imprint for the 3 products)

My problem is that the imprint cost has quantity discount regardless of the combination of product A, B or C that the clients order.

For exemple: one could order 50 x A, 25 x B, 25 x C = 100 units total

Then the client would get the 0 to 100 units imprint price. (the imprint price gets lower for every 100s units)

My problem is that I don’t know how to design this in cs-cart. I’ve tried with options, promotions, configurable products, quantity discount…there is always something missing or it doesn’t give the expected results.

If some one knows how I could achieve this or how I could do it easier another way, it would be appreciated !