Packtier adds one block to a product page that offers the product in packs: 1 unit at the normal price, 2 units cheaper, 3 units cheaper still, and so on. The shopper picks a size and colour for every unit, sees a running list of what the pack contains, and adds the whole pack with one button.
A tier can be a plain volume break, a buy X, get Y free deal, or a tier that adds a free gift, and any tier can earn real free shipping. You can also A/B test two or three versions of an offer against each other.
The widget comes in three styles - Cards, Rows and Table - that you choose and tune in the theme editor, with no code (section 5.1).