Does she play an instrument? If she plays the piano or guitar, she could go to a decent studio to record her singing and her instrument. It doesn't have to be studio-quality imo, as this music producer probably wants to use this demo to show her ability to his record company. I would recommend Standing Waves for a decent demo recording but it could be pretty pricey. Otherwise you could do what Bassix has suggested, go for either home or live recording.