With the new October 10th update to the steam client, valve has added an actual "wishlist" tab to view the wishlist in the store in big picture mode. The new update, however, now removed anyway to add a game to the wishlist. After selecting a game from the store page, and going into the store page of that specific game, there is no where on the page that says "add to wishlist.

It would be nice if the feature was reinstated.