Midwest Service Closeouts via eBay offers the Grassology Grass Seed 3-lb. Bag 6-Pack for $19.99 with free shipping. That's $3 under last week's mention and the lowest price we've seen. (It's the best deal now by $40.) It purports to grow roots that are four times deeper than ordinary grass. Each bag covers 750 square feet.
Note that these bags have sell-by dates varying from 2/16 to 11/16.