According to the latest supply chain leaked intel, Apple doesn't have to eat much more in the way of costs associated with their newest iPad Air 2 compared to the older iPad Air. The latest report indicates that Apple only pays $1 USD more to have an iPad Air 2 built than it cost them to have the previous gen iPad Air crafted.
Despite that, it looks like Apple's profit margin on iPads has dropped a bit more than that single dollar would suggest. Here's a quote with more detailed info,
While Apple's profit margins may have shrunk a few percentage points, Apple is still dramatically higher than any and all profit margins any of their Android competition can muster.