I have/used to...
I was pretty active in the Orygun Cowboys shoots out at Tri-County Gun Club, starting out in the early 1990s, until the club somewhat "imploded" due to "internal strife".

Now, most of my fellow shootin pards, shoot either at Albany or The Dalles.
We used to have some FANTASTIC shoots out at TCGC in Sherwood and for several years, hosted the "Northwest Regional" which we called "Orygun Trail's End".
I took pics of some of our activities out there using my little pocket digital. (Pretty crude and low res from back then when I only had Dial-Up and needed to upload pics at phone speeds)
At our big Regional shoots we'd have all the Top Dogs from all over the nation show up. Famous Cowboy Action personas like champions, Evil Roy, Longhunter, Holy Terror (about 15 yr.s old then), 2 Gun Dana, Dixie Bell, China Camp, Lead Dispencer, as well as our own champs, like Loden B. Kwik and Johnny Colt and a whole bunch of other "fun" folk from all over the map (I saw shooters from Hawaii, Wisconsin, Minnesota and Virginia there).
Of course all the close-by shooters from WA, CA, ID and NV were there too.
You can see some of my pics here:
(Hope the Mods don't get upset...they're NON-Commercial/my own pics links

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http://home-and-garden.webshots.com/...6398mJSduPYSSl
http://sports.webshots.com/album/43388696bmBQEB
http://sports.webshots.com/album/45471893NMgPyd
http://sports.webshots.com/album/45888602SyewAV
http://home-and-garden.webshots.com/...81879900XIeKOC
http://home-and-garden.webshots.com/...83585138FYiTCP
http://home-and-garden.webshots.com/...85900478vTsjHx
http://home-and-garden.webshots.com/...0743wyQGAvrSMp
As far as "How Expen$ive" is it?
You'll note that in the photos there are lots of "old farts" (both men & wimmin) and youngsters (who are often their grandchildren like Evil Roy and his grandaughter, Holy Terror). Somebody's PAYING for all those "guns 'n gear"
But realistically, you can get by with a Cowboy Hat, some Cowboy Boots (of whatever style you prefer), jeans and a "westerny" shirt.
Getting "into it", if you do it gradually, you can manage. I always bought lots of stuff on sale from a place in Arizona called "Wild West Merchantile". They'd often have "Bargain Basement" deals and I'd grab those up when I could.
I got "into" CAS because I already HAD a bunch of the proper "old tyme" guns that I thought I'd never get to "use".
Back when I started, it was quite a bit different than it is today. Back then most of us shot revolvers in .45 Colt or .44-40. Today many still do, but using "full power" loads that group is called "Warthogs".
Today there have emerged lots of "gamers", those intent on winning at any cost. Their gear has morphed from traditional "old west" leather into something that's close to "fast draw" in its design. Their rifles and revolvers are highly worked over ("slicked up") to be ultra fast and smooth. The exceedingly popular "Toggle Link" designs of the 1866 and 1873 Winchester replicas are often "short stroked", a modification that saves ~1" on the lever throw that adds up X 10 shots to maybe 1 sec. quicker on their stage's time.
The gamers usually shoot guns made in .38 Spl., and they're loaded with "pipsqueak" loads that have just enough energy (and NO recoil) to make the metal targets go "tink"!
Of course you don't HAVE to go this route, I didn't as I was mainly just shooting for fun.
For a choice of revolvers, most use either ecconomy Italian made clones of the Colt SAA or else Ruger Vaqueros (an iron sighted Ruger Blackhawk in "cowboy" calibers), either New Model (smaller, like a Colt) or original model which is pretty much the Blackhawk frame.
Other's use '94 Marlin rifles, and there's a whole bag of tricks in slicking them up too.
So to recap, most popular revolvers are: SAA Clones, Ruger Vaqueros (but Ruger Blackhawks are o.k. in "Modern" Category which permits adjustable sights) .357 Magnums can be used with .38 Spl. ctg.s and .44 Magnums can be used with .44 Spl or even .44 Russian or .44 Colt which are all SHORTER than .44 Mag, but FIT

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Most common rifles are: '92 Winchester (or clones), the clones being in .38/.357, .32-20, .38-40, .44-40 (original calibers), .44 Mag.
'94 Marlin either originals in the same BP calibers as the '92 Winchester above or else "modern" new-made Marlins in .38/.357, .44 Mag. or .45 Colt
And (mostly) Italian replicas of the Henry Rifle, '66 Winchester or '73 Winchester (all, in the Italian clones, using most of the SAME internal parts)
For shotguns it's pretty much either various Double Barrels, either w/hammers or hammerless (but NO Ejectors, Extractors only) OR '97 Winchester Pumps or their Chinese clones. Sometimes you'll see some '87 Winchester (John Browning designed) Lever action shotgun clones, now being made in China (but mostly they're somewhat awkward to shoot).
There are special classes, like Frontiersman (Cap 'n Ball revolvers, Lever rifle loaded with BP Cartridges, and Double Barrelled shotgun loaded with BP shells, SMOKEY!), Duelist (shooting revolver one-handed only), Double Duelist (shooting one handed, one revolver in each hand), Wild Bunch (using a 1911 or Broomhandle Mauser AND a Revolver w/Lever rifle and '97 shotgun) and some others.
At big matches (like Regionals) they'll have special "Side Matches" for Pocket Pistols, Derringer, Speed Rifle, Speed Pistol, Long Range Rifle-pistol caliber, Long Range Rifle-Rifle Caliber (this is where your .30-30 could be used) and Long Range Rifle-Single Shot (this is for Springfield Trapdoors, Sharps, Win. 1885s, Ballards, Remington Rolling Blocks etc.)
Whew! That was a mouthful (and now I've got typer's cramp)
Hope that explains it (a little)?
