Windex is on sale @ 2/6$ at WM. Snapsaves has a cashback offer of 3.50$ WUB2, plus if you have the 1$ Windex coupon that was available through here: https://www.rightathome.ca/Offers/Pages/default.aspx , you get it for 0.25$ plus taxes.
Maybe Windex is also on sale or cheaper elsewhere and could make it free???