I'm always on the lookout for the perfect white noise machine - everything on the market has a fault in my opinion!
The Marpac Hushh seems to be pretty close to prefect though.
It is plays constant white noise to mask unwanted noise and is rechargeable (using a USB cable) so no running about searching for batteries in the night. It plays three white noise sounds (bright, deep and gentle surf). It comes with a little clip to easily attach the Hushh to the buggy or carseat when out and about.
We have the Hushh in stock now!