Requirements:
Alliance character
Engineer skill level 105
Some pocket money
You will make Bronze Tubes to earn some money, to make 'em, you need 2x Bronze Bars and 1x Weak Flux.
Step 1.
Go to AH and buy Bronze Bars (20 for about 1-2g).
Step 2.
Now find a anvil and start making Bronze Tubes. When you have the Bronze Tubes, put each one to AH for 50s-1g.
Now, why do they sell? They are needed for quest at Duskwood called "Look To The Stars".
Remember to break the stacks of Bronze Tubes to single one!
The flux can be bought at Engineering Supplies merchants and Blacksmithing Supplies merchant. About 90 copper for one.
Alright, this is how I made/make easy gold, it worked for me...
Give it a try!