We use "White noise" app from app store. Its free. We have it on our phones and tablets, so this way we are always covered. Works great.
We bought ours from target or Walmart. It's "Mind Scapes - Sound Therapy" it's white noise and a clock all in one. Was a lifesaver when kids were babies, that was about 16 years ago and it's still being used.Thank you, but we don't take our phone with us and I don't have a smartphone for apps. I'd prefer a physical machine. Thanks anyway.
We use the Marpac Dohm-DS at home, but when we travel, we use the HoMedics: http://amzn.com/B00A2JBMRE