RGB-to-NTSC/PAL composite video encoder
Cadet II RGB Encoder is an RGB-to-NTSC/PAL composite video encoder for video synthesis systems. This product will begin shipping on January 18th, 2016.
http://www.lzxindustries.net/product/cadet-ii-rgb-encoder/
Available as an assembled Module and as a DIY project.
No info about availability.
$179