We don't know exactly why they're trying to clear some 360s out of their stockroom, but, were we in a betting mood, we'd bet that it has something to do with the invading 360s that include HDMI connections. Out with the old, in with the new, as it were. There's no similar sale on Elite or Core models. If you don't yet have a 360 though, it's a fine bargain. We don't know how long it'll last though, so you may want to act fast.
[Thanks to everyone who sent this in]