There's only one piece of Haste-imbued blue wow gold Plate, so this one should be easy. Brigg Smallshanks inside Utgarde Pinnacle will give the quest to kill King Ymiron with Vengeance Be Mine!. You can get this quest at Level 78, and can be completed in normal or heroic modes, so pick up the Platehelm of Irate Revenge. It looks exactly like the melee DPS plate, so be careful when choosing your reward.

Unfortunately, there aren't any Plate shoulders with Haste, so you might as well pick one with Crit. The best would have be the Ferocious Pauldrons of the Rhino -- yellow-socketed for more Haste Rating -- which drop from Gortok Palehoof in Heroic Utgarde Pinnacle. You're going that way for the helmet, anyway, so you can hope to get lucky. If you don't get the drop, you can have a Blacksmith craft Ornate Saronite Pauldrons or Brilliant Saronite Pauldrons, both of which are fairly cheap to make. The Ornate ones are a visual match for the helm, but the Brilliant shoulders are better for PvE since stat points are wasted on Resilience.

Lastly, there's the option of getting the Pauldrons of Morbidus, a reward from the quest The Flesh Giant Champion, the end of a quest chain in Icecrown. It takes a bit of opening up to do as the wow gold quest is phased and has a bunch of prerequisites, but if you do all the quests in the zone, you'll eventually end up there. As an added bonus, it shares the same graphic as the Ferocious and Ornate Pauldrons, so you won't look like a clown heading into your first raid.

There's only one piece of blue Northrend Plate that has Haste, and that's the Patina-Coated Breastplate, which is a BoE zone drop from Heroic Halls of Stone. You can try to farm the instance, but it might be better to farm the Auction House where it's likely to sell for no more than 200 Gold. Because blue and epic items come easily in Wrath, many blue BoEs sell for cheap. If you can't get this, don't worry, there are some good alternatives.

Similar to the chest, there's only one piece of Plate that has Haste for the waist, and it's a BoE world drop called the Belt of Crystalline Tears. It's a Level 77 blue, so it shouldn't cost too much and a few wow gold times of checking the Auction House should yield some results. On the other hand, there's a perfectly good alternative which has no Haste but Crit and a yellow socket which you can plug with a Haste gem, instead. The Girdle of the Warrior Magi can be bought from the Kirin-Tor at Revered status. This should be a servicable belt until you can get better in Naxxramas or Heroics.