Well most people buy PR4 domains because of the legit backlinks it already have, so traffic is not an important factor to look at. You're buying the backlinks the site have, not the traffic in most occasions. Then you can use it for a 301-redirect or a blognetwork etc.
On BHW its worth 52 USD as you can get it for that price in BST. But if your domain for example have some strong backlinks from big newspapers etc, it might be worth more. If some guy needs it to 301 his own domain because it have some niche relevant backlinks it can be worth alot more!
