Coming from someone who got the Halo Reach Legendary Edition, Killzone 3 Helghast Edition, Alan Wake Limited Edition, Dead Rising 2 Limited Edition, the Gears of War 2 Limited Edition, and the Halo 3 Legendary Editions all at deep discounts, unless you absolutely need all this stuff right away, you'll want to wait a few months before purchasing this.
These things are hardly "limited" and they depreciate in value mere months after release here at Amazon and at your local retailers. They take up space for so long and they depreciate in value so they get marked down at a large discount.
Unless you absolutely need it right away, you can probably snag it later at or around 70-90$. You can still get the Killzone Helghast Edition for 79.99 when it was originally 129.99. I think the numbers speak for themselves, folks.