The longevity of the PvP gear is one of the reasons why I just recently converted to full PvP.

Two seasons Old - you can buy with honor only or as its the case now, Emblems of Conquest (so Heroic Badges). Only set is available or maybe some vendor in orgrimmar has the rest.
One season Old you can buy with rating (very low), little Honor and very few arena points. Offset you can buy with just Honor.
Current Season you buy offset with rating+honor and set with rating, honor and arena points.

So, normally, when a new Season hits, taking this for example, Deadly will disappear, Furious will be bought with Emblems of Triumph, Relentless with Emblems of Frost and Wrathfull will replace Relentless.