At Canon, buy one select Photo Paper Pack and get another four packs for free. (Add one pack to your cart; the other four are added automatically.) With $5.99 for shipping, that's tied with last week's mention as the best deal we've seen on photo paper from Canon since last Cyber Monday (when free shipping applied), and it leaves most items at large price lows. Prices start at $7.99. Deal ends September 21.
A best bet is to buy 5 Canon Photo Paper Glossy 4x6" 50 Sheet Packs for $7.99 plus $5.99 for shipping. (Add one pack to cart; the other items are added automatically.) That's $2.80/pack and the lowest total price we could find by $22.