Ouch, 100 Excaliber @ $425 and some think Lapua's expensive. I looked at the Excaliber back when I was researching 338's and one of the reasons I didn't consider it for too long was the expense of brass, limited sources of availabilty and limited info readily available compared to other calibers for example here on LRH. Having said that if your set on Excaliber=great. Here's a link for cases that are re-formed from a more readily available caliber therefore they have the parent case headstamp. Beware though as I'm not sure if dimensionally they are exactly the same dimensions as true Excaliber brass. 100 @ $342 in case your interested. Just curious and maybe I was under the wrong impression but, I thought you were contemplating getting a 338 rifle. Since your searching for brass so soon does that mean you already have a 338 Excaliber rifle?
338 Excaliber Cases - Obsolete Brass - Obsolete Cases
338 Excaliber Cases - Obsolete Brass - Obsolete Cases