Making money with engineering

Making money in the age of Northrend
The Mote extractor remains the Engineer's unique resource extraction tool, and so remains a source of revenue for the engineer in the Wrath of the Lich King expansion.

End-game level guns remain a source of wealth. Engineer-crafted ammunition remains the best available, and with a guild one can acquire a set of steady customers. (Auction house sales still remain viable at the top end.)

Surprisingly, pets make a come-back as a source of income due to the pet collection achievements. While there was an early market for the motorcycle mounts (among the most wealthy on each server), this market dries up quickly. The remaining people seeking them will generally have a guild member who can craft it for them (given sufficient resources) by the time they can afford it. On the other hand, with level progression available to 80, fewer engineers are gaining the Consortium reputation required for Elemental Seaforium Charges, expanding the market for those who have the recipe. Typically, though, this will be a 'tips' market, as the engineer seeking parts for her flying machine will be able to provide all the parts for the charges.

A slight resurgence of quest-required items can be expected as people go back through low level quests while working on their Loremaster achievement.

The Mote Extractor
Perhaps the single most useful item for engineers is the Zapthrottle Mote Extractor. With the Wrath of the Lich King expansion, several regions in Northrend have clouds containing Crystallized Air, Crystallized Water, and/or Crystallized Fire. When combined with a flying mount extracting these clouds for resources becomes practical.

Note that there are clouds of Motes in several regions of Outland as well. Market for those, though, is largely for players practicing their trade skills; end-game materials has moved on to the crystallized materials.

Guns, Scopes, and ammunition
As in times past, there is a market for end-game guns. There exists both a warrior-tank gun (the Armor Plated Combat Shotgun) and a hunter weapon (Nesingwary 4000).

There is an indifferent market for high end ammunition. The majority of hunters will have some member of their guild who can craft the ammunition devices at low rates. And warriors do not typically buy ammunition in large amounts. The greatest demand, then, is from hunters preparing for raids who do not have the time to ask a guild member to create a box for them.

At the lower ends, demand is variable. As the average level on the server goes up, the cost of lower level materials increases, and the number of lower level characters for whom the ammunition would be useful declines. Between these forces, custom made ammunition for hunters remains a specialty market (for when "cost is no object").

While there is some market for scopes, the speed of leveling means that scopes are often overlooked until quite late. And once a hunter has his ultimate weapon, he will typically only need a single scope.

Guns

 * 80 Armor Plated Combat Shotgun
 * 80 Nesingwary 4000
 * 70 Gyro-Balanced Khorium Destroyer
 * 70 Ornate Khorium Rifle
 * 70 Felsteel Boomstick
 * 69 Adamantite Rifle
 * 63 Fel Iron Musket
 * 60 Core Marksman Rifle
 * 56 Flawless Arcanite Rifle
 * 50 Dark Iron Rifle
 * 47 Thorium Rifle
 * 39 Mithril Heavy-Bore Rifle
 * 36 Mithril Blunderbuss
 * 24 Moonsight Rifle
 * 21 Silver-plated Shotgun
 * 19 Lovingly Crafted Boomstick
 * 16 Deadly Blunderbuss
 * 5 Rough Boomstick

Arrows

 * 80 Iceblade Arrow (91.5)
 * 72 Saronite Razorheads (+67.5)
 * 62 Adamantite Stinger (+43.0) - created via Adamantite Arrow Maker
 * 52 Thorium Headed Arrow (+17.5) - Acquired by completing either of these quests which require 1 stack of 200 Thorium Shells.
 * Arrows Are For Sissies (from Artilleryman Sheldonore in The Commons, Ironforge; repeatable)
 * A Fair Trade (Orgrimmar) (from Bounty Hunter Kolark in Valley of Honor, Orgrimmar; repeatable)

Bullets

 * 80 Shatter Rounds (91.5)
 * 72 Mammoth Cutters (+67.5)
 * 62 Adamantite Shells (+43) - created via Adamantite Shell Machine
 * 57 Fel Iron Shells (+26)
 * 52 Thorium Shells (+17.5)
 * 44 Mithril Gyro-Shot (+15)
 * 37 Hi-Impact Mithril Slugs (+12.5)
 * 30 Crafted Solid Shot (+8.5)
 * 15 Crafted Heavy Shot (+4.5)
 * 5 Crafted Light Shot (+2)

Scopes

 * 70 Sun Scope (+40 ranged haste rating)
 * 70 Heartseeker Scope (+40 ranged critical strike rating)
 * 70 Diamond-Cut Refractor Scope (+15 ranged damage)
 * 60 Stabilized Eternium Scope (+28 ranged critical strike rating)
 * 55 Khorium Scope (+12 ranged damage)
 * 55 Adamantite Scope (+10 ranged damage)
 * 50 Biznicks 247x128 Accurascope (+30 ranged hit rating)
 * 40 Sniper Scope (+7 ranged damage)
 * 30 Deadly Scope (+5 ranged damage)
 * 20 Accurate Scope (+3 ranged damage)
 * 10 Standard Scope (+2 ranged damage)
 * 5 Crude Scope (+1 ranged damage)

Pets and mounts
With achievements for the number of companions one has collected, engineered pets are much more in demand. The Lifelike Mechanical Toad is a particularly rare recipe, and the pets created with it can bring a premium from hardcore pet collectors.

Small pets
 * Mechanical Squirrel Box
 * Lil' Smoky
 * Pet Bombling
 * Lifelike Mechanical Toad
 * Tranquil Mechanical Yeti

At skill of 450, and with reputation with the respective faction, engineers can craft a mount: The mounts are race-restricted however. Engineers may charge a hefty fee to craft one of these mounts, or sell the pre-assembled item for a fixed fee.
 * Mechano-Hog
 * Mekgineer's Chopper

Engineers can make flying mounts too:
 * Flying Machine 150% speed increase
 * Turbo-Charged Flying Machine 280% speed increase

Tradeskill Items
While these items are not required for end-game content, Engineers are still the sole source of them.

Professions
 * Alchemy: Recipe: Goblin Rocket Fuel
 * Blacksmithing: Plans: Inlaid Mithril Cylinder
 * Leatherworking: Salt Shaker
 * Fishing: Aquadynamic Fish Attractor

With the fishing daily quests providing Sharpened Fish Hooks, the Aquadynamic Fish Attractor has a smaller market.

Quest Items
Mithril Casing
 * Chasing A-Me 01 (2)

Advanced Target Dummy
 * Gizmo for Warug (Magram Clan Centaur)

Gyrochronatom
 * Gyro... What?

8 x Hi-Explosive Bomb 8 x Unstable Trigger
 * That's Asking A Lot

1 x Overcharged Capacitor
 * Just a Few More Things...

1 x Deadly Blunderbuss
 * Warsong Saw Blades (quest)

1 x Adamantite Frame
 * Additional Materials
 * The Soul Cannon of Reth'hedron

Services
Services are using an item to do a service in exchange for money

Using Seaforium Charges you can open locked boxes. Just like a rogue, usually you do it for a fee or tip.
 * Lock Opening

Occasionally a player may need a mailbox or vendor in an out-of-the-way place and will pay a small fee for you to use MOLL-E or Jeeves. Places where it may be required as there are no such facilities nearby: in a raid or dungeon, Darkmoon Faire at the opposite faction's zone, items for large turn-ins of rep such as Ravenholdt which may be stored in the mailbox.
 * Mailbox or vendor

Everyman Items
These items do not require a skill to use or equip. The majority of them are in low demand, though.

Consumables
 * Flame Deflector
 * Ice Deflector
 * Discombobulator Ray
 * Ez-Thro Dynamite
 * Ez-Thro Dynamite II

Devices
 * Ornate Spyglass

Equipment
 * Voice Amplification Modulator

Professional Items
These items are crafted by engineers, for engineers. In most cases, they are specialization recipes (gnome or goblin) that do not require that specialization to use. In other cases, the recipes are reputation awards, and the products can be sold to those who have not yet done the required reputation grind.

Equipment

 * Goblin Rocket Boots
 * Gnomish Rocket Boots

Gnome Engineering

 * Gnomish Alarm-o-Bot
 * Gnomish Harm Prevention Belt
 * Gnomish Mind Control Cap
 * Gnomish Net-o-Matic Projector
 * Gnomish Rocket Boots
 * Gnomish Shrink Ray

Goblin Engineering

 * Goblin Jumper Cables XL - obsoleted by the Gnomish Army Knife
 * Goblin Mortar
 * Goblin Rocket Helmet
 * Goblin Sapper Charge
 * The Big One