I'm not entirely sure if this will work, because I don't have a paypal account to test it with.
This is my idea on a way to get any amount of gold, for any server, for basically nothing.
The first thing you need to do is go to woworder.com and click the "WOW GOLD" link at the left. Scroll to the bottom of the page and choose either the US link or the EU link.
Next thing to do is to choose your server. Once you do so enter the amount of gold you want. I recommend something reasonable like 1000. You will notice the price stays at 0.00.
Click the Buy Now link and enter your character/server information. Then it will go to the Paypal part. From here enter 0.01 in the Unit Price, and click update totals. Once again, I'm not entirely sure this will work, but I guess someone with a Paypal account could try it.