Amazon has the 18-Count Charmin Mega Rolls Ultra Gentle Toilet Paper on sale for $20. Add 3 to cart for $60 - $10 off multibuy discount = $50 with free shipping (extra 5% off for 5+ S&S orders). Roughly $16.67 per pack (the previous low was $19).

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