Woot offers Bona WM700018159 Kemi USA Cleaner, Hardwood Floor Refill Gallon, 1 gallon/128oz for $9.99 (orig. $29.38). Free shipping for Prime Members. 

Product Description:
128 oz. (1 gallon). gently clears your floors of dust, dirt and grime. Dries quickly with no rinsing needed. Greenguard gold certified to ensure a safe formula. Safe for all unwaxed, polyurethane finished wood floors. 

• Gently clears your floors of dust, dirt and grime
• Dries quickly with no rinsing needed
• Greenguard gold certified to ensure a safe formula
• Safe for all unwaxed, polyurethane finished wooden floors