Would only be good if priest had enough good low cost spells to design a deck around auctioneer. Since they don't it's extremely slot inefficient, and priests have mass dispel anyway. Either increase the cost and give it draw or remove it and add something else. For example, a solid 2-3 drop with a silence battlecry would be fine.
Shadow Word: Pain:
It gets 2-for-1d by any minion with a battlecry or a deathrattle and can at best 1-for-1. It also doesn't have the benefit of being versatile the way a damage spell is (being able to go for face or help kill a bigger creature). Replace it with some interesting form of low-cost board clear/removal based on damage rather than just killing, instead.
My suggestion would be Mind Sear: 3-drop, deal 3 damage to a primary target minion and 1 to the minions on either side.
More damage spells also has the benefit of making priest spellpower decks viable, thereby increasing variety in deckbuilding.
Divine Spirit and Inner Fire:
Awful cards. Just because they pull off a turn 5 OTK one in every 100 games doesn't mean they're good or provide good gameplay. Generally, by the time you're done pumping 3-4 cards into a minion it will get removed, tinked or silenced. The few times this doesn't happen it's equally frustrating and pointless for the enemy. They are simply bad design and should be removed. Replace them with early game stuff so that priests can actually beat rush decks without needing wild pyro in every deck and then praying you actually get it along with PW:S and Smite in your opening hand.
For Holy fire lower the cost to a 5 drop and lower it's healing to compensate. At 6 cost it competes with Cairne, Sylvanas, Temple Enforcer and Cabal Shadow priest for the slot. Tbh maybe reduce the cost of temple enforcer and it's stats/battlecry as well and make it a 5-drop too. There are too many great neutral 6-drops and almost no good 5-drops (aside from azure drake, which is good in spell power decks only) since the Sylvanas nerf.
Shadow Word: Death:
Making things like Ysera and twilight drake impossible for priests to outright remove with their removal spell perpetuates the issue of seeing tinkmaster in every deck ever. Just increase the cost to 4 and include things with 4 attack please.
Tbh I'd love to see Mindgames, thoughtsteal and Mindvision gone too and replaced with something actually consistent, but that's probably asking for too much. Oh well.