The Xenith Monk is a very powerful card. Put as a tank with very low mana it can be a game changer. I'm trying to upgrade mine but I see prices for the card going up all the time :-)
I have picked this post on behalf of the @OurPick project and it will be highlighted in the next post! 
Really the current price of the cards compared to a while ago is high, I'm also waiting for a good time to buy cards from him, but it's still a great investment for the long term for this price.