Newegg.com has the Sennheiser Closed Active Noise Cancellation Headphones PXC150 for a good price.

Item has a rating of 4/5 from 176 reviews

Note : You need an older headphone to get this deal.

Pricegrabber Price : $48.88 ~ $119.00 Shipped

1. Newegg Price : $43.00
2. Rebate Price : -$25.00
( You need to mail it along with an old headphone. Find an old dirty one around the house or ask your co-workers/neighbors for any headphones they might've stole from the airplane, etc. If you must, you can buy a cheap one on eBay )
Final Price : $18.00 Shipped After Rebate