The rebate isn't all Newegg offers, either. As the kind folks at Slickdeals found, you can shave the case's price by a further $30 by entering the following coupon code on the checkout page: EMC713DANTE. Slickdeals says users must sign up for the Newegg newsletter for the code to work, but some may find that a small price to pay for the $30 savings.
After the coupon and mail-in rebate, the P180 should end up costing just $49.99. You'll have to cough up $18.99 for shipping, but that's still far less that what anyone else charges for the case.
Update: Unfortunately, it looks like the $30-off promo code is no longer valid. The mail-in rebate deal is still running, however.