As far as I'm aware, purchasing PVP weapons (with resilience on them) requires arena points, and as such you'll have to do arenas for them (while you do get 25 arena points for every battleground daily you complete, that's a really slow way of getting arena points). See the vendor in Dalaran, for instance. (Also see this old question on the subject.)
As for PVP sets, I have to admit they confuse me greatly (I'm hardly a PVP sensation, hell I barely PVP at all). I think they go like this:
- Sets that are two seasons old (currently the Deadly set) are sold for honor; they're also sold for Emblems of conquest, or (less) honor and some arena points. This is the set you would've seen being sold in Orgrimmar.
- Sets that are one season old (currently the Furious set) are sold for either Emblems of Triumph, or honor plus arena points.
- Sets that belong to the current season (currently the Relentless set) are sold for arena points.
Non-set pieces are always bought with only honor, but the higher-end ones require arena rating to wear. The best you can get at the moment is, I think, the Furious batch (unless the Relentless batch has already gotten dropped to no requirements, in which case that would be it).
So, if you want to only spend honor, you're stuck with the Deadly set and Furious off-set pieces. (Though, if you're wearing T9, you might as well go grind heroics for Emblems of Triumph, and get the Furious set.)
As soon as the next arena season hits, the Relentless set and off-set pieces should become easier to obtain. But I'm not certain when that will be, or how things will change. Like I said, I'm not really a PVPer - I'm just relying on Wowhead, and that seems to be a bit un-updated in terms of PVP gear.