We're currently attempting to confirm this information with some of our other retail contact, while our source is attempting to get a full page scan of the Kmart flyer. There is still no word on how this $50 price reduction on the Premium model will affect the Arcade or Elite Xbox 360 consoles, currently priced $280 and $450, respectively. More images can be found after the break. We'll update as soon as we learn more.
Update: Full-page ad pictured here.
[Thanks to everyone who sent this in; with special thanks to that "Anonymous" someone!]