This week from September 22-28, Toys R Us America will be offering BOGO 50% off ALL LEGO building sets with no theme exclusions. However, it appears that they have labeled all of the online exclusives/hard to find sets like modular buildings as “Hot Price item!” which mentions that it cannot be combined with additional discounts.
In addition, they will also be offering a free $10 Toys R Us Gift Card on purchases above $40. This offer (with coupon) is valid in-stores only. Thanks to forum member UnknownUser for the tip.