Petco has a decent subscription price on K9 Advantix right now, but what makes this great is that their flash sale 25% off coupon "FIESTA" does not exclude repeat deliveries!

For the Extra Large 6 month supply…

Repeat Delivery Price: $ 61.24
FIESTA coupon discount: -$ 15.31
Final Cost: $ 45.93 ($ 7.66/month)

Shipping is free for orders over $ 49, so add a filler item $ 4.09 or higher and you’re good to go.