Amazon has the 18-Count Charmin Ultra Strong Toilet Paper (Super Mega Rolls) on sale for $25 - $5 off automatically at checkout = $20 with free shipping on $25+ or with Prime (extra 10% off for 5+ S&S orders).

For you toilet paper aficionados keeping track:

18 Super Mega Rolls = 108 Regular Rolls
18 Family Mega Rolls = 90 Regular Rolls
18 Mega Rolls = 72 Regular Rolls
18 Giant Rolls = 47 Regular Rolls
18 Double Rolls = 36 Regular Rolls
18 Regular Rolls = 18 Regular Rolls