Hi, and I'll say welcome to the forum. But, I must admit your post has me a bit confused. I have read it several times, and wonder if you are exchanging the word "Casings" for possibly "Cartridges"????
If you don't want to "Reload" then yes you could buy already manufactured "Cartridges" (casing, bullet, powder, primer) with steel cases and just shoot and forget them. But, if you want to "buy brand-spanking-new casings and load them myself"... you would need to buy Brass Casings and of course all the equipment and manuals and supplies and so forth to be able to do so... Even if it were possible to buy new steel cases to reload(which I don't believe it is), you would still need all the equipment and so forth, and it would not be cost effective at all.
So, perhaps you could expand a bit on what your intent actually is.