Foremost advice for finding most things is to look at their item level, see what planet lists that level as part of its level range, and go do all the Heroics. It's not an easy answer, but it usually helps. If that fails, look for item boxes of that level, or kill a bunch of silver- or gold-star mobs around that level. Item boxes might be mission rewards (another reason to check the Heroics of planets of the appropriate level range), Crew Skill results (primarily Treasure Hunting, but I think Slicing does it sometimes too), and some can be found on the Commendation vendors. The box's item level is listed in its description, and it will give items of exactly that item level.

Unfortunately, on a female character, the Introversion and Inspiration Vests are a lot less "vest" and a lot more "bra".

Aside from the unavailable Battlefield Commander's Vest (a few pieces of the set are on the Light Side vendor, but alignment vendors don't sell any chest pieces), are there any moddable medium armors which are white in color? Not counting the Vendetta stuff which is Agent-only. Mostly I'm looking for something with the Sith Warrior medium armor look, sort of vaguely like I've got here, or the Bladestorm stuff and things like that. I'd take a moddable white-colored Imperial uniform, too, but I'm pretty sure nobody's found one of those yet. Anyone encountered anything like that?

At level 50, I'm still most fond of the Darth Vader-esque Gilded Xonolite stuff: http://i42.tinypic.com/wpdz.jpg I can't quite remember where it came from, but it feels like Tatooine stuff, and the level range supports that (26ish). It may have been The Long Goodbye, from Lapad Dula at Outpost Thorazan in the Dune Sea. Even though it's a Heroic 2+, it's soloable if you're sneaky, or if you're willing to die and then just revive near the sarlacc out of aggro range from the mobs. The craftable Resilient Lacqerous Vest also has the same appearance. I actually don't like the set's pants, so I use Bladestorm Leggings instead -- nice, simple, black-and-grey, and you probably already have them by the time you want them. (Ignore the horribly mismatched red boots in that image. That was pre-1.2 and they now fit nicely with the rest of the set despite not actually being part of it.)

Medium armor is fine. You just have to find the cool-looking stuff. http://i42.tinypic.com/wpdz.jpg

In the first half or so of my leveling, I was running Carnage spec and loving it. Massive Force Screams were wonderful and way too much fun besides. As the levels wore on, though, I found my survivability -- and, perhaps more relevantly, sustainability -- to be rather lacking, particularly coming to this from my Operative, who could basically go forever without stopping. Having to Channel Hatred after every single fight was annoying, and quite simply not something I wanted to deal with. So, despite not particularly wanting to, I switched to Annihilation, and the combination of self-heals and Quinn kept me going without stopping all the way to level 50. I told myself I'd switch back to Carnage once I hit 50, since I wouldn't need to do the leveling run-around anymore. So, now I'm level 50, still as enamored of Marauder as I was when I began, but I've not yet switched back to Carnage, because I failed to account for daily missions. Sustainability remains a useful trait to have, for that reason alone. So, I pose a question to the Marauder-playing community: At level 50, does Carnage no longer have the sustainability problems it had in the mid levels? I'm willing to keep Quinn, much as I'd rather use Jaesa, simply because it seems a healer companion is non-negotiable for DPS classes, but will that be enough? Or will I find myself scrambling back to Annihilation just so I don't have to stand around healing up after every single fight?

The RD-07A Vendetta set (http://www.torhead.com/item/8lMoakB/rd-07a-vendetta-jacket) looks very similar to this, though the clothing underneath is grey instead of white. It's apparently a world drop, probably on Belsavis. I found mine on the GTN; I've seen a couple go up, so your best bet may just be to keep an eye on that. Haven't seen anything that looks EXACTLY like it, though, with white under-clothing and all, and obviously the helmet's nowhere near the same. Judging by the icons, the TD-06B Eliminator Headgear or TH-16A Master Medic Headgear might have that appearance, but the set's matching chestpiece isn't the same.