Target has a coupon code that will get you 15% off any LEGO set on their website! This applies even to the high end Direct-To-Consumer LEGO sets that rarely get discounted. The entire list of LEGO sets can be found here. Sets will sell out fast once word gets out so make your orders quickly.
Use coupon code TGTKZN2T at checkout. This coupon code can only be used once per account so make all your purchases in one order. The coupon should also apply to almost everything on the Target website.
Update: It looks like Target has disable the coupon code for LEGO but it should still work on most other things on the website.