Nothing to do with pride; I have no desire to spend money on a costume just to go see if I like it. ...
Same reason why I wont do deals with people that want a BOS....or buy a gun from Wild West Traders because they want to take a picture of you to match to a 4473
You aren't asked to "dress authentic" if you wanna show up for a few matches and shoot them to see if you like them. A "grace period", if you will. Wear whatever your heart desires; shorts, t-shirt, baseball cap, and cleats. That's just fine. They don't expect folks to sink money into a sport that they aren't sure about.
We've folks show up without all 4 of the required firearms (2 revolvers, rifle/carbine, and shotgun) and we've loaned them guns and ammo to shoot for the day. You won't find a friendlier bunch of "competitive" shooters.
One of the reasons for the paid back attitude is the lack of a prize table. If you place, you get a certificate that says where you placed. That's it. Since you're not shooting for a $3,000 Noveske or somesuch, folks tend to not be quite so uptight.
Targets are all steel. Hit or miss. 3 of your fellow competitor count hits/misses. Majority wins. If there are 3 different totals, shooter gets the benefit of the doubt.
There are stages where you have to sing, or receipt a stanza from a poem, or throw a tomahawk/knife/lasso, or spit on a target, or sit on a mechanical horse and shoot while it goes up and down.
By far, CAS is the most laid back competitive shooting I've ever done, and I've done damn near all of them. Part of the sport is the romanticism of it all, so dressing up is part and parcel of the package. CAS has been around for over 20 years and there have been many changes, but I don't see that one. Changing.
Exceptions are always made. There was a guy that came straight from work, didn't have time to change, he shot in his Dairy Queen uniform. We all laughed about it and no one bitched.
If you change your mind and wanna give it a try, let me know. I'll dust off my gear and go shoot with you. You need to borrow anything, I've probably got it.
Semper Fi!