I would say the cheapest way to obtain the RAF pets is to wait for a WoW Battlechest sale. There was a special sale
over the holidays (that's since ended), but if you can wait for another one similar to that, it will help reduce the price of each RAF pet.
The quickest way to obtain the pets after you've gone through the necessary steps of setting up the accounts is to purchase game time from the Blizzard Store. RAF accounts receive free game time, so adding a credit card subscription means you have to wait longer for the pets since the game time isn't charged to your card until the free time is up. Game time from the store is applied immediately.
Here are the steps I took to collect the RAF pets (I go into a little more detail on my blog post
1. Sent my current Battle.net email a RAF invite while I was on my main character.
2. Went to my email inbox and opened the RAF invite. Clicked on the link provided inside (takes you to a Battle.net URL).
3. I chose the option that said something like "I already have a Battle.net account".
4. Added the "starter edition" account to my existing Battle.net.
5. Next I needed to upgrade from a "starter edition" account to a "standard edition" account. (Purchased and applied a WoW Battlechest to the RAF accounts)
6. Once it was upgraded to "standard edition", I headed over to the Blizzard Store and purchased game time for the RAF account.
7. I repeated these steps to get more "standard edition" accounts.
Other things to note:
- You can only have a total of 8 WoW accounts on one Battle.net.
- You do not need to log into the game on the RAF account to complete the process.
- It takes a total of 7 full days after game time is applied (and registered) to the RAF accounts before your main account is eligible for the pets.
Hope this helps!