I would get a media player type device for the second TV and run network cable. Chromecast, AppleTV, Roku, Generic Android Media player, etc. With a TV/DVD player that can do DLNA you would not even need an additional media player.
If you just going to run the second TV as an additional pc screen then you won't be able to play different media on both TVs at the same time. And you are going to have to go to the primary pc TV to start/stop/pause/etc.
A 20m hdmi cable would cost over R500 and a 20m vga around R300.