Charmin Ultra Strong, Mega Rolls, 6 Count Pack (Pack of 3) 18 Total Rolls is only $15.47 shipped when you sign up for Subscribe & Save at checkout and “clip” the $.25 coupon.
http://www.amazon.com/gp/product/B003WJBF0U/
The mega rolls equal 4 regular rolls so this prices out to $.21 per roll.