TERA for $5 at Amazon right now. Yes, less than the price of subscribing for a month.
Too good to be true? Well, there are limitations. The only version thusly on sale is the digital download, meaning that if you'd rather have a physical copy, you'll have to pay a bit more. It's also only the standard digital edition with no extra bells or whistles. Still, it's the game and a month of subscription time for less than a fast food lunch, so if you still haven't tried the game and have a desire to do so, your time is now.
[Thanks to Segun for the tip!]