A couple years ago I built a digital signage application using the Chromecast. However, it was very apparent that it was a terrible platform for digital signage

A couple years ago I built a digital signage application using the Chromecast. However, it was very apparent that it was a terrible platform for digital signage. The Chromecast is designed from the ground up for sharing content on a TV. It is not designed for a 'kiosk' type of situation where the device always boots to your content. With these limitations, I built a digital signage app based on Chromeboxes instead (http://metascreen.io http://metascreen.io). The Chromebox has a 'kiosk' mode which allows you to specify which app should run when the device boots up (very critical for business digital signage). If you are looking for something super low cost, checkout digital signage solutions based on the Raspberry PI. Would fit your expectations nicely.