Pre-Naxx Death Knight Gear

This guide will help you to get your Death Knight ready for Naxxramas 10 and then you can progress on your own from there.
I will suggest the best gear and a couple of alternatives for the item for those who may not have the time or the gold to get the best.

Head

Spiked Titansteel Helm - This helmet is crafted from a Blacksmith. It is very good, has a meta slot as well as a nice amount of hit.

Faceguard of Punishment - Comes from the quest Vengeance Be Mine! in Utgarde Pinnacle. The large hit is good to make up for the lack of it elsewhere.

Chitin Great Helm - Drops from Anub'arak in Azjol-Nerub (Heroic). The gems are nice and it has alright stats.

Shoulders

Pauldrons of the Lightning Revenant Drops from Ionar in the Halls of Lightning (N)

Mantle of Volkhan Comes from the quest Diametrically Opposed, in the Halls of Lightning

Shoulderplates of the Beholder Drops from Moragg in The Violet Hold (N).

Chest

Bonegrinder Olympics - This breatplate drops from Prince Taldaram in the Old Kingdom (Heroic).

Breastplate of the Solemn Council - This breatplate is a rep reward. It requires revered with Wyrmrest Temple.

Engraved Chestplate of Eck - This breatplate drops from Eck the Ferocious in Gundrak (Heroic) this is good because of the slots and the large amount of hit rating.

Wrists

Vengeance Bindings - These wrists are extremely cheap and are the best you will get for a while. Snap them up at the AH or get a blacksmith to make them.

Cast Iron Shackles - These wrists are a world drop and so if these are in the Auction House you may want to pick them up.

Golden Limb Bands - These wrists Krik'thir the Gatewatcher in Azjol-Nerub (Heroic).

Hands

Gauntlets of Dragon Wrath - These hands drop from Cache of Eregos in The Oculus (Heroic)

Gauntlets of the Culling - These hands come from the quest A Royal Escort in The Culling of Stratholme.

Plate claws of the Dragon - These hands come from Cyanigosa in the The Violet Hold (N)

Waist

Flame-bathed Steel Girdle - This waist come from Cyanigosa in the The Violet Hold (Heroic)

Clinch of Savage Fury - This waist come from the Argent Tournament, it require 10 Champions Seals.

Verdungo's Barbarian Cord - This comes from exchanging 40 Badges of Heroism with the vendor in Dalaran.

Legs

Staggering Legplates - These are fantastic and I highly recommend you get them, good stats, slots and loads of hit rating. Drops from Ingvar the Plunderer in Utgarde Keep (Heroic)

Legplates of the Oculus Guardian - Drops from Varos Cloudstrider in The Oculus (H)

Legplates of Bloody Reprisal - You require exalted with Wyrmrest Accord for these, I don't really recommend getting the rep just for these.

Feet

Death-Inured Sabatons - If you have the rep with Knights of the Ebon Blade I suggest you get these. You require exalted.

The Obliterator Greaves - Drop from Zuramat the Obliterator in The Violet Hold (Heroic)

Spiked Titansteel Treads - Made from a blacksmith, require Titansteel.

Hope this helps you gear your Deathknight!