It's hard to give any feedback without knowing a bit more about what your aims are with the deck. Is it for ladder or is it casual. Is it a budget deck or can you afford to put in some legendaries? If it is for laddering you might have to consider the current priest meta game decks. The thing about the meta is that it makes a deck very un-original. But those seem to be the best options of you want to get a high rank. Again I don't know what your aims are, so any suggestions will be very minor.
I don't think the egg really suits what I think you're going for, neither does Gadgetzan auctioneer. In my opinion a gadgetzan is more for late game control oriented decks which is slightly heavier on spells. Yours is more minion focused and early, to mid game - mainly mid game. That being said I don't think stormwind champion contributes very well to the deck either, as it constitutes a heavy mana crystal investment for a situationally powerful card text and mediocre stats. If I were you I would take out the abovementioned cards with perhaps one shadow word death as well. Perhaps put in another defender of argus or two dark iron dwarves instead of the auctioneers. Another card that works very well with your setup is wild pyromancer seeing as you have the means to trigger it multiple times whilst still keeping your own minions alive. A good alternative to stormwind might be Maexnna. Her stats and ability look like they would suit a priest very well. Her ability will also allow you to punch through any big taunts or 4 attack minions which are untargetable by your removal spells. Mind control also seems to be an outlier in your deck, as the concept I think you're going for doesn't really have the late game in mind. A good alternative, if you really want some late game punch, is ragnaros. If you're on a budget perhaps an auchenai soulpriest for the aoe combo with circle of healing or a cabal shadowpriest. If you want another spell instead of mind control I'd suggest Shadow Madness as it's almost always a two for one trade and suits your early to mid game focus perfectly.
my two cents' worth
