In their shop, that’s just $76, and a square inch $113. Mounting on polymer film must be expensive, as, on copper, 15cm×15cm costs only €396 (less than $2 per cm²)
You get a coverage of “> 97%”, so it seems manufacturing isn’t that good yet (or, maybe, they keep the good stuff for themselves and sell the scraps)
That said, apparently it's been going down in price quite rapidly by order of magnitude: https://www.graphenea.com/pages/graphene-price#.XyDfAGkpCNw