The Sennheiser PC360 has gone way up on price, best I can find is $215.
Go to the Electronics Expo website, put the Senn HD558 into the cart, use the coupon code "BOUNTII".
Should be around $80 less then the PC360, I'm sure you can get a decent mic for $15 to $25.
Asus Xonar DG is about the best bang for the buck sound card.
PC360 can be found at $200 from razordogdeals at ebay, but $80 off on hd598 sounds good :)