There are two $5 off LEGO Coupons available at coupons.target.com right now (list of sets that are eligible are listed in our LEGO Coupons Forum). Coupons can be used instores at Target and are stackable with sales such as Heroica Castle Fortann for $19.99 (reg.$29.99). With the coupon, you can get it for $14.99 plus tax which would be half price. Both coupons expires on November 23, 2011. Thanks to forum members hebc and solo606 for the news.
*The sale price for Castle Fortann has also been priced matched at Amazon.com for $19.99 with no tax.