If you haven't seen one you are just having bad luck on the random numbers. We consistently have these dropping and are auctioning off in guild chat.
As an aside Adam, You are all aces, going above and beyond! A Very Merry Christmas and the Happiest of New Years from a grateful player... Merry Christmas and a Happy New Year to everyone.
Personally I would like to see power sources phased out of the game. The compromise way of doing this is 4 "epic" powersources via a non-bottlenecking true epic quest that a player can hand back to the final NPC to switch it to any of the 4 permanent epic power source rewards. One power source to rule them all (or so it goes...) In the meantime, good on the devs for putting old/equivalent drops of something semi-stalled in the game as per player requests on the beta forums.
As much as I really do appreciate the work that went into making these and answering the feedback of players to have new power sources - power sources should go the way of the Dodo. Why have a Dev waste so much time making these items at this point? Just add the appropriate stats to visible pieces. Or! Just add another 7/8 slot to visibles and replace power sources all together. It really is a long in the tooth, out dated EQ feature from back in the day to grow player power outside of the AA window and give players something to do.
I think the ability to ramp up for a raid, or use a less expendable item otherwise is a good thing. Just like tribute. They aren't enough power to be required to beat things but they certainly are nice for those of us that have them.