Runestone Treasure Chest are obtainable in a ton of zones, if you know where to look.
Depending on the zone you find them in, you’ll either acquire rare items, uncommon items, or even common items–equipment and potions alike. Don’t scratch them off your list just yet; they could be worth something on the AH depending on your realm.
Outlaw Rogues can track treasures.
Demon Hunters can use Spectral Sight to seek any nearby.