I have the World Ends with You and in the first five hours of gameplay I can tell you that it is the best DS game I have ever played. Just pay the money. It's depth makes it entirely worth it.
I think mine was 20 off 80, but yeah it's still alive. I ordered on Sunday and being delivered tomorrow (Wednesday). Can't complain about the shipping time.
I just got a Pro from buy.com for 329.99 using the 20 dollar off coupon from Google Checkout.
If it was B&M, it would be 375 with tax.
Plus I used my AmEx, so that's 1.5% back, another five bucks.
Fifty buck savings. Not bad.