1.
)    Message boards and forums.
These are great places to find Warcraft gold for sale since there are so many people with more gold than they need that are looking to make an extra buck.
In other words, they'll split with their gold for cheap while giving you a good deal.
2.
)    Auction sites and similar buyer/seller meet up sites.
This includes Craigslist and eBay.
These are a little bit more "iffy" just because you never know if you'll get scammed with something like this, but it's worth checking out.
You can find people who are auctioning off, bartering or just selling their gold for dirt cheap.
These are a great place to look.
3.
)    Social networking sites.
On Facebook or MySpace? Look up a Warcraft group and see if there are any members that have Warcraft gold for sale-you're bound to find at least 10 groups related to World Of Warcraft so it won't be too hard to locate those.
Next you just have to see if anyone has any gold they want to part with, for a discount of course.
4.
)    Gaming magazines.
This is a bit more in depth of a search but vendors of gold do advertising in World of Warcraft related magazines and computer gaming magazines.
Check these out because sometimes you can find a good deal on Warcraft gold for sale.
Of course, you can always just get your gold for free.
If this sounds better to you then you should check out a good World of Warcraft gold guide that can have you earning 297+ gold an hour-with ease.
This way you won't have to pay for gold ever again, you can just earn it yourself and save all your money.