The following text is from the catalina coupon I received:

Congratulations! Now, save even more!

Buy any POST CEREAL (10 oz or larger) between 8/17/7 & 9/9/7

Buy (3) ................. get $2.00 ...
Buy (4) ................. get $3.00 ...
Buy (5) or more ...... get $4.00 ... coupon Off Your Next Order

All items must be purchased in one shopping order.
Limited to product in stock. No cash back.