I got a fantastic email from someone, we'll call him Dave, regarding my profession conundrum.
You specifically mention farming low level dungeons for greens to DE to skill up enchanting. Its a common mis-conception but this is not "free" materials. Likewise if you mine your own ore for JC the materials there are not "free" either.
If you can get cash in any other way that is faster than this then mining is NOT a money making profession, it is in fact a money LOSING profession. It is my experience that just doing dailies is better cash/time than mining/herbalism and therefore Mining is note "Excellent" at gold making, it is horrible. Quite literally the only reason to have mining is for smelting and on an alt this works just fine.
If you need mats to skill up, check what they cost, figure out how long it would take you to farm them, and then figure out what your gold rate per hour doing dailies is. 99% of the time farming them is a money loser...just buy em.
What Dave is talking about is opportunity cost. The time it takes you to farm instances for mats to level up Enchanting or mine ore to level up Blacksmithing, is by definition, time you could be spending doing something else. Most of the time, according to Dave, that something else will yield more gold per hour.
He is correct, but that only tips the scale towards mining. Mining is still a great money maker. Let me explain.
Let's say a stack of saronite ore sells for, on average, 20g on your server. Let's say that it takes you 30 minutes on average to farm a stack of ore. You now know that mining is worth 40g an hour. If you can get cash in any other way that is faster than this then mining is NOT a money making profession, it is in fact a money LOSING profession.
That would be true if you were spending that 30 minutes 'farming', that is flying around the Basin looking for stuff to mine.
On the other hand, if I'm out doing dailies and happen to see a Saronite vein, and I walk over to mine it, I have lost only a few seconds. I don't have the same opportunity cost, because the gold I make from selling that ore/bars didn't cost me any time.
Another example would be last night where I was flying over to Wintergrasp to do Vault of Archavon, and a I passed a Saronite vein. If I was a miner, I would have stopped to two seconds and gotten the ore. It wouldn't have cost me any time, or had any opportunity cost.
I have decided this much. It's down to Mining or Blacksmithing. The ring enchants from Enchanting are nice but they come in AP and Spell power flavors. Those don't scale with any buff. Blacksmithing sockets provide raw stats like STR or STA. Those do scale with buffs.
There have been two changes to Engineering that make me want to wait until after 3.1 hits to change professions.
First, there is a rumor that bosses in Ulduar are going to be 'skinnable' by Engineers and that the drops from that 'skinning' will include the parts for the motorcycle. I need to give it a week or two to see if that is true or not.
Second, the Engineering pets Lil Smokey and the Pet Bombling are going to be drops in Gnomergran. I want to farm them both up before I drop the profession.