Cost to build off a second bedroom?

We own a 1 bedroom condo that was designed as a 2 bedroom but modified to be a 1 bedroom with a very large living room. We would like to build a wall to create the 2nd bedroom as per the initial blueprints. Is anyone able to advise as to how much this may cost? It would be a simple drywall with an air vent from the living room and possibly an electrical outlet connection or two. Thank you for your advice!