At the Atrium Bar of Intercontinental Hotel where we stayed in Sept, the coffee was 7 euro, the same price as a beer. I am sure this is doubled the price compared to a generic roadside cafe. Though Cafe de la Paix is even MORE expensive than Atrium Bar - you can walk into Cafe de la Paix from Atrium Bar inside hotel, and of course you can go in Cafe de Paix from Avenue de l'Opera.
The prices were outrageous. Good thing we had complements from the front desk because they messed up our room.