I know the $20 off $50 has been posted but this is a great deal for anyone interested in a new filter. Just purchased mine however I had to pay for shipping since there are no AAP's near me.
K&N Air Filter
Coupon code: ES123 ($10 Off $30 / $20 Off $50 / $30 Off $100)
$30.48 with in store pickup selected.
Shipping was $8.66 for me.