While it's true that leather bound Bibles have a retail cost of $50-$75, the manufacturing costs are a lot less. I used to work for a retail bookstore chain and the discount for Bibles was around 50%. This means that the retailer paid the distributor $25 for a Bible that would be sold for $50 retail. The distributor received a similar discount from the publisher, and the publisher got a discount from the printer.
Keep in mind that the Watchtower employs slave labor, whereas a for profit printer employs union labor. Since the Watchtower doesn't provide retirement or medical benefits for their workers, the Watchtower has minimal labor expense. The cost of materials would be their biggest expense in producing a Bible. Plus the Watchtower doesn’t have to pay out royalty fees, as the NWT is their own invention.
So my guess is that the new deluxe NWT costs the Watchtower only $2 or $3 to print.