I'm into a somewhat different mindset , course I always run against the wind as it were
CAS is a fantasy where you can get in deep or not so deep with your impression.
SASS offers immersion as simple as a pair of Jeans , Ropers , and long sleeve shirt and many style hats .
Or there is Silver Screen, or many sources of period western wear. Some do militia or Military.
It is wide open...as much or little research as you wish.
Now, I enjoy the persona as much as the shooting aspect. I like to read the history over ballistic, coronagraph results and the latest trick of the month Gun tune...
The advise you are getting, is to attend , shoot a verity of guns and view the experience and range atmosphere as to your kit.
There is good number of leathersmiths right here in CAS City , look at your budget, befriend a shooter or two and listen to their suggestions.
Good hunting as it can be a enjoyable quest