With patch 5.4.2, we can transfer BoA items to any realm.
And, there are some BoA items that can be purchased with gold, and can be vendored for usual vendor price too.
Here is the list of items.
Of course, the cost of such a way is very high. You only get sellback price, that is 25% of what you spent on item (27.7% with discount perk).
So, to get 100 gold on another realm, you need to spend 400(360 with discount perk)
The best way to transfer wealth without a loss is still Battle Pets, but this way has some differences:
- it doesn't depend on either of your realms AH and Economy
- it's instant, you don't need to find a buyer/seller for the goods
Overall, I think it's good way to give your alt on a new realm some starting gold. Or if you find something super-cheap on AH there, and want gold right now before it's snatched.
P.S. Keep in mind that guild heirloom armor has significantly reduced sellback price, and shouldn't be used for this.