From the title of this thread, I could have sworn the topic would be my favorite Craigslist app- Craigslist Notification.
(The app title has changed now to something slightly different)

https://play.google.com/store/apps/details?id=com.mufumbo.craigslist.notification.android

Works a treat! Set each search parameter, as well as the option to include areas based on miles from zip. Set your update frequency in the settings.

Good stuff! Hope it works for you.