People have already contributed to where you can find the barriers via waypoints. Below is a consolidated easy-to-grab list you can copy (thanks Currently and Blynkiboo), and throw into something like the Paste addon, should you use TomTom
/way #2472 43, 84 South barrier
/way #2472 41.3, 62.8 Northeast barrier
/way #2472 30.6, 62.9 Northwest barrier
If you don't have TomTom, but a different waypoint addon that makes use of the /way feature, here is the same list, without the map id:
/way 43, 84 South barrier
/way 41.3, 62.8 Northeast barrier
/way 30.6, 62.9 Northwest barrier
Keep in mind, that if you don't have TomTom or a waypoint addon that makes use of the /way feature, you can click on anyone's coordinates, in Wowhead, and choose the in-game map pin option. Then all you have to do is go into the game, hit enter into the chat window, paste what you copied and hit enter a second time. In your chat window, you'll see something like [Map Pin]. When you click this, it will stick the map pin on your map. Yes, this process is a bit convoluted and should at least maybe steer you towards getting TomTom. It really will make your life easier.