Right now, TRU is having a Buy 2 Get 3rd 90% off sale on all LEGO, no restrictions. That's roughly 30% off depending on if the sets you buy have mark up and assuming you buy 3 similarly priced items. Not sure when this promotion started or when it ends because their online site doesn't say squat. But I'm gonna guess it started today and ends
Update: JamesBenjamin from the forum reports that it's good today and tomorrow, Saturday.
Thanks to Billy for writing it in.