First I just want to say that this carries the same risk as buying any other RAF game time currently. I am unsure if anyone has gotten their mounts removed, but there has been a recent wave of people getting their RAF time removed. That being said, you can use this method to turn $7 into 3 months of game time between 2 accounts and level with 3x XP bonus due to RAF!!
1. First, buy a $5 starter edition on sale which includes up to WOTLK and one month free game time.
2. Then, set up a second email address that you would like to use this starter edition on. From your main account, send the RAF request to this email address you just created.
3. Go to the link through the email address and use your starter edition code to unlock the one month game time and WOTLK features.
4. Now for the exploit. Activating the starter edition earns you nothing on your main account. You then purchase an unlock code from one of the sellers on these forums and enter this code into RAFed account. This game time will be temporarily activated and will last less than 24s but the one month game time on your account will not be removed. Add a second of these $1 unlock codes to activate a FREE heart of the nightwing mount on your main account! In total you will then receive one month of game time on your main account, one month of game time on the second account, and then a free 2 person mount.
Using this in conjunction with actually leveling a toon or two to lvl 80 will maximize your usefulness especially if you only want to do this for a month. If you create the second battle.net account with your same last name, you can then transfer any toons to your main account for $25.
Note: Since the recent RAF removals have been happening, maybe you should wait until your subscription is about to run out to add the "unlock code" to your RAFed account. If anything, you will be able to get a free week using this technique, or more accurately a week for only $1. If you are lucky, you will get to keep the entire month!