There is a Catalina promotion at Target through 4/17 that includes Windex products. A Catalina is a coupon that prints at the register after you pay; use it like cash on future purchases. Here are the details:

Buy 2, Receive $1.00 Catalina
Buy 3, Receive $2.00 Catalina
Buy 4 or more, Receive $3.00 Catalina

Buy Three Get One Free through 5/14
Buy 4, Receive $3.00 Catalina through 4/17

Use two $2.00/2Windex Products (coupons.com)

Pay $5.12, Receive $3.00 Catalina

Final Price: $0.53 each, when you buy 4