Howdy and welcome!
First thing I want to say (after welcome) is to slow down, you'll get a more harmonious outcome.
There are thousands of guns that will be available to you over the next year or two. It is a rare fella that is shooting the same guns he started off using, tastes and experiences change.
One of the outstanding aspects of the CAS culture is the desire to help out a new shooter. Not just online, but at the matches as well. So find a local club and visit, make yourself known and ask what guns you can try out. I know this sounds wierd. And sometimes a fella can be having a bad day and not take it the right way, but that's rare. If you were down here, I can guarantee that if you call/email before you show, you could try out just about every gun made for CAS.
If you are going to shoot 45s, then check out
www.ammodirect.com for a better price on ammo, you will need it until you decide to reload. But if you aren't a frequent shooter, 1000 rounds can last you at least 6 months. I'd suggest a Uberti replica of the Colt for your first gun, if you are going 45s. There are many available, even with the price increases, for under $400, some even under $300, but you'll have to have a good eye to avoid getting stung. CR gave you the best tip: buy from a cowboy looking to change. The guns are usually set up right and the seller is almost always a good pard.
Get good leather, as you can afford it. First, buy a belt that fits you. It's easy to loan a gun and a holster, but if you don't fit my belt, then it's troublesome. Big Ed of SPS (an advertiser here) is having a sale, his work is excellent. There are other choices as well.
Don't worry about clothes or a cart for a while. Just wear a decent cowboy hat and no tennis shoes, you'll be fine. I wrote an article on clothes, I'll see if I can dig it up.
Adios,