Zen Cart Big Chooser

Zen Cart Big Chooser allows you to flexibly create product based (rather than dollars spent based) discounts.

Big Chooser is configured using a series of PHP commands in a special purpose language designed for creating discounts.  Because of this, while it is powerful and completely configurable, it is really intended for developers customizing sites for their clients, not for store owners with no programming background. If you are a storeowner, Discount Chooser may be a better option for you.