There are a lot of cheap Android TV Box that works. However, not all will work perfectly with RM Plugin.
Here are a few criteria too look out for:
1. Android version
RM Plugin requires minimum Android 4.4 and above
2. Android UI
What you need to look out for are those that use standard Android UI rather than some badly customized UI for TV with remote control yet not actually running Android TV Leanback UI.
RM Plugin is compatible with either standard Android UI (input via keyboard & mouse or touchscreen) or true Android TV Leanback UI (Sony Android TV, Nvidia Shield TV), not those in between.
3. Background app
Make sure the OS of the Android Box allows app to run in the background for Alexa Bridge and HTTP Bridge to stay running in background all the time. Many Tv Box will immediately kill the app when it is not currently showing on screen. An example is XiaoMi TV Box. Some users have reported that by changing to Nova Launcher, it may allows your box to run apps in the background.
Also, many devices come with built-in power saving feature that kills long-running or background apps to save power consumption. This option should be disabled for RM Plugin.
You may try to change your device settings to keep the screen always awake. This will improve the stability of Alexa Bridge.
4. Official Google Play Store
RM Plugin app was designed to work only when it is installed directly from Google Play Store. This is to prevent any form of piracy or virus infection when installed from 3rd party sources. Side-loading from APK file to any devices will result in 7-days trial, which will eventually expires.
5. Processor
RM Plugin is only compatible with ARM processors.
Majority of cheap Android TV box in the market are using ARM architecture. You can simply buy a cheap box and have no worry about this.
However there are a few rare ones and probably higher-end boxes uses x86 architecture. This is more of a worry for more advance and savvy users with rare hardwares.
Here are a few devices we have fully tested during our development:
• HiMedia Box models
• Google Nexus TV Player
• Sony Bravia Android TVs
• Remix Mini
• Nvidia Shield TV
These devices are 100% not supported
• XiaoMi TV Box (can't run app in the background)
• FireTV (no Google Play Store, see this)
• Those without official Google Play Store
• Remix OS running on x86 hardware (x86 is not supported)
These may work, but you're on your own, we do not support them:
• Android running on a PC hardware
• Android running in VirtualBox, VMWare, etc...
• Android running on Raspberry Pi, Beaglebone, Pine64, OrangePi, etc...
The follow devices are confirmed by customer to not work with Alexa Bridge at all (not able to discover devices)
• Motorola Moto G
• Vodafone Smart First 7 (VFD 200)
• Some Huawei devices