Target is having a 10% off Lego advent calendars sale this week. That puts the City and Friends calendars at $0.09 and $0.05 per piece, respectively. The Star Wars one is $0.12 per piece on sale. The "Spend $50 or more get a $10 gift card on LEGO" promotion is still going on too.
Kohls has one Lego set, a few Mega Construx, and a bunch of Cobi sets on sale online. Not sure what the brick & mortar retail situation is like.