Have you ever seen cross-faction pets? I mean horde with alliance pets, and/or alliance with horde pets.
The thing here is: there is no other way a horde could get an alliance pet, or an alliance a horde pet, than the one I will show you.
This means: you can make very big amounts of gold by selling the opposite faction exclusive pets! They sell like popcorn! This is an insanely profitable way to make WoW gold, believe me! You could tell me "But, if these pets are exclusive, how am I supposed to take them to sell on my own faction auction house??" Well, let me fix it.
You can ask a friend from the other faction to do this or do it yourself by creating an alternative player from the opposite faction.
You need to buy a pet that is supposed to be exclusive to your faction.
Here comes the trick.
Take both players to the same neutral action house.
Yes, this is where you are going to "send" yourself these exclusive pets.
Gadgetzan or Stranglethorn, the one you like the most.
Keep in mind that you two must be at the same auction house at the same time.
You will understand why later.
Then take the exclusive pet that you want to "send" and list it on that auction house by a small fee.
Do not forget to set a buyout price, or else you could lose it and trash all the work! And the other faction player will then take the pet by paying the buyout price.
Result: you will have a player which has exclusive cross-faction pets that can be sold very well at its own faction auction house! Beware of a few things.
First, this is very important...
keep in mind that the player which "receives" the pet will keep all of the profits.
You can´t send anything to an enemy faction player by mail, remember? So, after the player takes the pet on the neutral auction house, he will keep all the profits.
If you have an opposite faction player, then there is no problem.
But if you asked a friend to help you, you could in exchange put a pet from your own faction at the same auction house, so you can "exchange" them.
Second, and this is very, very, very important too.
Keep in mind two factors when the pet is listed on the auction house: how many people are there at the same auction house at that time, and how much time passes until the pet is bought.
Why? Because if there are too many people at the auction house, or if you allow to pass too much time after the pet is put to sell, there are very high chances that another player could come and buy the pet, and you lose everything! Remember to be fast, it is very important! With this little trick alone, you could earn high amounts of gold.
You could sell exclusive pets for even 50, 80, or 100 or 300 gold each, depending on the market! Hope this was helpful for you!