If you can't find golden comets specifically, look for any red sex link. They are basically the same thing, golden comet is just a hatchery name for their particular type of red sex link.
This hatchery in Canada sells what they call Berg's Brown, which are red sex links.
You can get them delivered to fehrway feeds in winkler , and other locations. We've had bergs browns for 20 months , they lay jumbo eggs every day for 12 months , molt and lay every second day ..... mine are beginning to shut down we will have to put them down before spring .
Just so you know they lay lots of huge eggs these hybrids, but they have a short life.
I switched to heritage Rhode Island reds and Icelandics... many more happy years for these hens