No, no, you're correct. Those there are and available but you need Centurion commendations to purchase them and, at the moment, I'm unsure of where to get those. The lvl 50 blues on Corruscant are purchased with the normal warzone commendations that you get from any warzone.
As for the blue and purple, you are able to purchase the blue piece with WZ commendations and you can upgrade your blue to the purple by owning the blue and having a pvp artifact from somewhere. All lvl 50 pvp blues are able to be upgraded to purples with higher stats.
Yes I'm referring to the Voidmaster's robe. If you look at the "currency for" tab on torhead you'll see that it can be upgraded to a purple....which still, in my opinion, is not better than my lvl 40 orange seeing as how I like having absorption.
After talking to a couple guildies, it seems that it is in fact broken and we tanks do not get a lvl 50 pvp tank set like the JK. Guess I'm going to have to stack WZ and MERC commendations so that when I hit 50 I'll be able to try and get Champion gear from the bags you can guy from the PVP vendor on the fleet. Sigh, need a fix for this.....