(My game time expired yesterday, so I don't have all the gear for every single set written down).
Blood Knight (Paladin Only): level 60 PvP set, Archmage's Guile, Blood Knight Crest, Blood Knight Tabard.
Sunreaver Knight (Paladin Only I think): Judgement set headpiece, got the chest from Heroic Scenario bag, Sunreaver Tabard. Gloves, shoulders, pants, and belt are the SoO Heroic Paladin Tier. Sword comes from Lord Rhyolith in Firelands. 1h sword is one you can find on AH (I forget what it's called, maybe Mercenary blade?) Shield is a rare drop from old world mobs, and I forget its name too. Cloak drops from Black Temple, I think.
Sunfury Champion (my favorite and available for all plate wearers): Head is level 60 PvP Paladin headpiece, there are lookalikes. Shoulders, Chest, and Gloves drop from Sunwell Plateau. Shield is level 70 PvP gear. Pants, Belt, Boots, and Cloak drop from ICC (Heroic 25 for the armor, Normal or Heroic 25 for the cloak). Sword drops from the Frankenstien boss in Naxxramas. Tabard is Thrallmar Tabard, but looked sinister, like Blood Knight but with a little bit of Burning Legion added in. Ret weapon is level 70 PvP 2h Sword.
Sunreaver Honor Guard (All plate wearers): Shoulders are Paladin Tier one (or healing plate heirloom). Chest is Patina-Coated Breastplate. Gloves are Gauntlets of the Chosen. Belt is Goblin Girdle. Pants are Avenger's Legplates (or Leggings, I forget which). Tabard is Sunreaver Tabard. I forget the boots. The Polearm is from WotLK questing, I believe.
Purple Holy (All plate wearers): Purple Judgement set from BC dungeons, Shield is Titansteel Shield Wall, sword is Continuum Blade.
King (Not all Plate, just fun outfit): head: Crown from Fire festival. Shoulders, chest, gloves, pants, and off-hand are all from Sunwell Plateau. Belt, Boots, and Sword are from Sunfury Champion set.
Holy Warrior (Paladin Only): Paladin Challenge Modge gear. Sword is Phantom Blade. Shield is Silvermoon Crest. Tabard is Silver Covenant Tabard and is only there to see how it would look. I use Argent Crusader's Tabard in-game.
Scarlet Blood Knight:Head - Faceguard of Determination
Shoulder - Commander's Pauldrons
Cloak - Cloak of the Inciter
Chest - Bloodscale Breastplate
Shirt - Red Workman's Shirt
Hand - Commander's Gauntlets
Waist - Belt of the Sand Reaver
Legs - Commander's Leggings
Feet - Commander's Boots
Weapon - Archmage's Guile
Shield - Shield of the Wayward Footman.
Shattered Sun Blood Knight (All Plate classes): Exalted plate set, with chest from Sunwell Plateau, Sword from Naxxramas, shield from Archimonde, belt from Ulduar, and Warbringer's Crown. Shattered Sun Tabard.
Cenarion Blood Knight: I forget, you'll have to look in Mogit for them.
High Elf Blood Knight: Saltstone set for shoulders. Pants and belt from WotLK quests. Silvermoon Crest. I forget the head, chest, boots, gloves, and sword. I think the cloak is from Malygos.
Gold Holy (Paladin Only): Judgement set with shield from Outland quests. I forget the sword.
Mehlar (Paladin Only): Shoulders from Blackwing Lair. Chest and pants are Paladin level 60 PvP gear. Hands, wrists, and boots are Judgement set. Sword is from Argent Tournament. Goblin girdle for belt. Tabard is Sunreaver Tabard.
Scarlet Crusader: Head and Shoulders from Blackwing Lair I think. Belt from AQ. Tabard of the Scarlet Crusade. I forget the 2h hammer, boots, and gloves. Wrists are Judgement set. Pants and chest are Paladin Tier 1, but can be bought by all classes at Darkmoone Faire.