I, not me, have tried it numerous times with buying skills from my rogue trainer, and from the mount trainer. If you are in the capitol ( sw ,IF,org, us, etc) or in an inn ( anywher gettign rested exp) Buy your skill ( only 1. otherwise you wotn have enough time) and VERY QUICKLY log out of the game. If you are in the wilderness( perhaps buying your mount skill) press log out . Open the trainer window, select your skill, and be sure to click train as sson as you have like 3 seconds less ( i tried it on 1 second) and it will work. This has worked 100% of the time for me. and it is verified.
EDIT: Noob Friendly guide (for mount)
AFAIK all mount trainers are out in the wilderness (non rested state areas)
1. Go to trainer.
2. Press ESC ( Main Menu)
3. Press Log Out
The timer should begin counting down.
3. Right click the trianer
4. Go to the training window.
5. Select the skill
6. Wait till the timer is like 2 seconds. To be sure, try to get it at 1 second, but its not my fault if your too slow.
7. Click train QUICKLY( before your 1 or 2 seconds expire)
You will log out, and when you log in, you WILL have your skill, AND your money."
FAQ:
1. Im not getting a timer when i hit logout, no luck with /logout either. Is anyone else having this problem?
When i do this it doesent give me a count down timer, it just logs me out. What i did do that worked is this, type in /logout (Don't Hit EnterYet). Purchase the spell and within the second hit the enter button
and /logout will logg u out. when u logg in your money is returned with the free spell..
/logout (buy spell) Enter Button
BTW: I have tested this two times today and worked both times in ironforge.
2. Where do I use this?
Use it only in the major cities where u get instant log out
use /logout
press train and and enter almost at the same time and u get the ability!
Ie. If you train in a city in which you are resting no matter where you are in that city (e.g. Ironforge, Orgrimmar, etc), you will not get a timer...it will log you out instantly. Go type /logout and DON'T hit the enter key until you purchase the skill...then quickly hit the enter key and you will log out. OR, you can find a trainer in a non-resting area such as a minor camp, port or town.