Target offers the Threshold Uptown Stripe Light Blocking 54x84" Curtain Panel in five colors (Blue pictured) for $29.99. Coupon code "MOMSDAY" cuts it to $26.99. With free shipping, that's $3 off list and the lowest total price we could find, although we saw two of them for $48 last July. They're thermal insulated and feature a grommet top.

Note that you can also get the 54x95" panel for $33.29 with free shipping via the above coupon. That's $4 off and the best price we could find. Both deals end May 7.