Thumb Score: +23

Update: The one-time purchase coupon is no longer there, but now includes $3 Amazon credit. Price is $9.70 after coupon w/ S&S.

Amazon [amazon.com] has 52-Count Swiffer Sweeper Dry Mop Refills for $12.94 – $2.95 – 25% at checkout = $6.75.
Shipping is free with Prime or on $35+ orders.

Savings
Coupon price $9.99 (clip on the product page)
25% off applied at checkout to first order.