What does it cost to level Engineering right now?

4.3kg in reagents at today's US auction prices, over about 118 crafts. Sell the results and it comes back to 4.3kg.

Where do these numbers come from?

The skill thresholds are read from the game client data for build 12.1.0.68914. The prices are the region-wide auction house, refreshed every few minutes; these are the snapshot taken at 15:57 UTC.

Why does the route change when I reload?

Because the prices did. The cheapest recipe for a stretch of skill is whichever one's reagents are cheapest at that moment, and that moves through the day.

Profession leveling · Cataclysm Engineering · US · prices as of 15:57 UTC

Engineering leveling 1 → 75 · Cataclysm Engineering

4.3kg in reagents over about 118 crafts. Sell what you make and it comes back to 4.3kg.

Start skill

Trainer recipes only

Recipe names carry the colour the profession window gives them: orange is a point every craft, yellow is three in four, green is one in four.

Before the first craft — buy it all at once

One trip to the auction house. Vendor lines are cheaper from the profession vendor than from the board.

ReagentNeedEachTotal

Elementium Bar×9424

2,325

×942,325

Lavascale Fillet×7410

Handful of Obsidium Bolts×519

×595

Volatile Fire×515

×578

Total4,276

Step 1 · Skill 1 → 25

Yellow→Green

Grounded Plasma Shield

trainer

About 64 crafts.272

per skill point11

Tinker's Kit×64

Step 2 · Skill 25 → 35

Orange→Yellow

Electrified Ether

trainer

About 12 crafts.445

per skill point44

Volatile Air×24

Step 3 · Skill 35 → 70

Orange→Yellow

Goblin Barbecue

trainer

About 37 crafts.2,889

per skill point82

Elementium Bar×74

Toughened Flesh×74

Lavascale Fillet×74

Step 4 · Skill 70 → 75

Orange

Heat-Treated Spinning Lure

trainer

About 5 crafts.667

per skill point133

Handful of Obsidium Bolts×5

Elementium Bar×20

Volatile Fire×5

Skill 75 — done. Now sell what you made.

Crafted itemUnitsEachTotal

Goblin Barbecue3750

3718

Electrified Ether1223

122

Heat-Treated Spinning Lure1062

106

Capped at what the market takes in 3 days, so a route never pretends to sell hundreds at once.

Back in your pocket4,254

What's worth crafting with Engineering right now

Questions

How this route is built

What does it cost to level Engineering right now?: 4.3kg in reagents at today's US auction prices, over about 118 crafts. Sell the results and it comes back to 4.3kg.
Where do these numbers come from?: The skill thresholds are read from the game client data for build 12.1.0.68914. The prices are the region-wide auction house, refreshed every few minutes; these are the snapshot taken at 15:57 UTC.
Why does the route change when I reload?: Because the prices did. The cheapest recipe for a stretch of skill is whichever one's reagents are cheapest at that moment, and that moves through the day.

A first craft pays Knowledge, not skill, so it is shown as a badge and left out of the craft count. Vendor reagents are priced at the lower of the vendor and the auction house.