As part of June's coupons (6/1/17 - 6/25/17), Costco will have a 45 pack of Cottonelle Ultra ComfortCare for $16.99. These are wide rolls and significantly larger and longer than the rolls you find on Amazon or at Target/Wal-Mart.
Costco - 1,264.5 SQ. ft in total, divide that by $16.99 = 0.013 per SQ Ft.
Amazon - 702 SQ ft. in total, divide that by $14.63 (16.13 - 1.50) = 0.021 per SQ Ft.
Regular price for this pack at Costco is $31.99 (link below).