Don't level one Engineer - Level two of them!
One of my alts is a Skinner/Engineer (from level 5). Another is Mining / Engineering (Dropped Skinning at 300/ lvl 50's). Any other alt over lvl 10 is a Herbalist or a Miner, or both.
Engineering requires a huge stack of mats to level up to 300 - Even the 200 mark, where you choose gnomish or goblin, still takes a heck of a lot of Bars.
I had all alts gathering and pooling mats for when I quit skinning to power level Goblin Engineering. (2 Engineers? One's Gnomish, the other Goblin. Both can use Jumper Cables XL, but only one can make them.)
Both happily made their way over the 300 mark, Repair Bots and Delicate Arcanite Converters have that effect on Skill levels.
BC came out. Absolutely nothing of any interest to me. Nice to Haves?, Sure, but nothing with any WOW factor.
2.3 came out. Now we have Epic headgear, blue headgears, toys, and a rather spiffy mount. Time to re-level Engineering. So I begin:
I'm levelling the Skinning Engineer (Gnome), but soon the Fel Iron Bolts and Casings turn grey, and I need a shed load more. Rather than waste the potential skin ups, I get the Mining Engineer (Goblin) involved. She happily makes the Bolts,Casings and Blasting Powders for me.
I soon make the (very obvious) connection: I've had 100 Fel Iron bars and 60 Adamantite bars, along with 2 Primal Fires and 2 Primal Earths (Not a lot of mining effort TBH) and turned them into a lvl 355 Engineer and a lvl 335 assistant. Engineer. I have 40 Adamantite bars left on one char, Making Shell cases will whizz the lower char up to the same level as the main, AND I can still get XP for them on the main.
Now I have an Epic to work towards, Some neat toys, a legitimate reason to roll for Primal Nethers, and best of all, a sense of accomplishment.
So: Try levelling 2 Engineers together. You could also use a guildie rather than an alt, if you don't fancy 18 months of chomping at the bit, waiting for Engineering's time to finally come.