go here and request 2 different free coupons for Excedrin Migraine and Excedrin Extra Strength.
You can also scroll to the bottom of the page and request a coupon for $3.50 off Excedrin PM. This coupon, when paired with a sale, should easily make for cheap or free Excedrin PM.
You will receive all of these coupons within 2-3 weeks via snail mail.
Thanks, Hip 2 Save!