The Xiaomi Mijia Paipai is a wireless HDMI transmitter that retails for just US$53.99. Resembling two Chromecasts, the Mijia Paipai operates over 2.4 GHz and 5 GHz networks to transmit 1080p content from up to 10 metres away.
https://www.notebookcheck.net/Xiaomi-Mijia-Paipai-A-wireless-HDMI-transmitter-for-streaming-content-in-up-to-1080p.500818.0.html