You started with Horde on Dalaran didn't you? What was your reason for making some Alliance toons, out of curiosity? Seems like you are splitting your time across both factions.
I like Goblins, I like Gnomes. If I could leave the Alliance and Horde and join a Neutral Faction like the Steamwheedle Cartel, I would.
Edit: also, as much as I enjoy the Goblin starter area, it gets tedious to play through Kezan and the Lost Isle multiple times. It's faster rolling a gnome.
How realistic is it for average Joe to pay for the monthly sub with gold? Money is tight like a tiger these days so I'd really rather go the gold route if possible.
With just one toon?
Inn - At lvl 2, you can start recruiting followers with Treasure Hunter trait, level 3 unlocks gold missions.
Warmill - follower upgrades starting at lvl 2, this will drastically speed up hitting those follower ilvl milestones and can be significantly cheaper than buying Frozen Arms of the Hero off of AH (650 ilvl boost for follower)
Trading Post - generates garrison resources from various crafting mats, these you can gather in your garrison or purchase from trader. You'll use the garrison resources in your Warmill. The lvl 3 trading post helps with rep grinds.
Warehouse - lvl 3 ups number of possible work orders for each building.
Salvage Yard - starts to pay off at level 3, you get a decent chance of follower upgrades and a lot of vendor trash. Sometimes you get crafting mats you can use in the trading post.
You would have to consistently farm heroic raids every week, and probably heroic dungeons as well, with the brunt of the money from older content coming from vendor trash.
It's a lot easier to pay for your sub with gold if you're doing it with multiple garrisons.