Some of you like me saw those cool looking outfits (among others) and just had to have them. then just like me you relised no matter what perks you had, what you did, or how you tried to kill them some clothes in this game just cant be obtained (not for those of us on 360/PS3)
well despite bethesda's best efforts to taunt us with clothes we cant have (shakes fist and other gestures) i have good news.

there are two obtainable outfits i know of so far, that no matter the system you play on, can be yours.

1st: obviously we all know about Ulfrics outfit, the only way to get that one is to (Spoiler) join the Imperials in the civil war line, complete it and loot the clothes. (Spoiler)

2nd: the second outfit (pair, there are two sets.) is located in the East Empire Company Warehouse, wich itself is just south of solitude. once inside the master level door (there may be a key but i didnt check) you proceed through the werehouse avoiding the gaurds. at the back right corner is a boat under construction, as you near it there is a shelf with clothes all over and around it. what your looking for is the Noble Clothes and fur lined boots, there are two sets and they must be stolen. their apearence is iddentical to the Jarl of whiteruns clothes.

Enjoy

if you find any other unique clothing please be sure to let us know

Awesome find.

Tavern clothes/boots from the dead tavern wench in Liar's Retreat.

I dunno if these are super duper rare, but I've never seen them for sale. Killing/pickpocketing a tavern wench might be the only way to obtain them othewise.

@ranmafan: thanks

@unclepain: the only other pair i have found other than killing/pickpocketing is Liars retreat as you have said, and a vampire in morthal.

Tavern clothes and boots seem to show up as loot, but very, very rarely.