You can search Ebay for some auctions. I bought my Denon AH-D2000 for 300 USD, including shipping and taxes.
I love my Denons! Maybe because they were such a huge upgrade from my 10$ headphones >.<
I don't know about the D1100 though, Never tried those.
You should search Ebay for a good price. I recommend you get the Denon 2000 if you can, especially if you find them in a much lower price =P
EDIT: I forgot to add that I know for sure that the Denon ah-d1100 has more bass than the M50, so it will suit you more if that's what you're looking for.
Edited by ArTIkBaNAnA - 9/9/11 at 2:44pm