I have been shooting CAS for about 7 years now and have had very good luck with Western and Wildlife Wonders in Washington State (they advertise in the "Chronicle"). Holsters run around $60.00 to $80.00 and belts around $100 to $125. I am a Silver Senior Gunfighter with average stage times running around 60 seconds.
Before investing large amounts of money in equipment, I would urge you to evaluate your average performance. Good equipment can cut seconds but usually fractions of seconds off your total time, but you will probably not beat younger shooters. It's not a fast draw competition; the holster must hold the revolvers securely and be easy to reholster, but you don't have to get too fancy. Beware of belts with many bullet loops; they get heavier and heavier as you get towards the last stage of the day.
I have also found the same thing to be true of short-stroke kits for rifles or revolvers. Good sights, that you can see well, will do much more for you than gunsmithing designed to shave time.
Just my two cents. I have a great deal of fun and will never be on the leader board. Just depends upon what you want. Also, I enjoy being period correct within reason.