How far apart are the TVs? If they are reasonably close together I would not rule out running wires back to the relays.
If you use a wireless system you will need some sort of Arduino (maybe a Nano) at each PC. The nRF24L01+ wireless modules are cheap and work well. This Simple nRF24L01+ Tutorial may be of interest.
Another option would be to set up a small web server on your PC and use ESP8266 modules to communicate with it using WiFi. The ESP8266 modules have WiFi and a microprocessor all in one package and can be programmed using the Arduino IDE. However if you are not familiar with web programming the nRF24s might be easier to use.
...R