How to configure that.. packs and combinations

[jviure]

Hi, I don't know how to configure the next scenario:

We've a ps shop with only one product (masks!). The product is 12€ unit (it has combinations, sizes..). BUT,  from > 50 units the price is 10€/unit, and from >500 the price is 500€/unit. I ve done this with catalogue rules, works Ok. What I need now is to create "pack" products. I.e we'll ve a pack 50 and a pack 500.  There ll be 3 "products" but at the end we'll only sell one product. If someone buys a pack50 and 10 individual units.. then this individuals units must have the acording price (10€/unit). It's possible to do that? thanks!