I personally think hearthstone has a near ideal business model. Everyone I know that plays it just doesn't mind chipping a couple bucks every now and then to do the arena (drafting mode). I think when alteil gets a draft mode that will have a similar effect where people don't mind purchasing a dollar or two for gran to play drafting mode, and at the end of the draft you receive prizes based on your performance (no fine details atm).
The Auction House will add a whole new dimension to the business model in my opinion, I have no idea how this will shape things overall.
With all things considered I think the prices need slight tweaks on some products/starters. I think it would be a good idea to have the newest set at lower price than the other sets until a new set comes out, then you make the 2nd newest set's price equal with the rest and the new new set's price cheaper (packs/boxes/gold boxes). Maybe have certain prebuilds cost less as well. More frequent sales would be nice as well, on unique products too. Perhaps have a limited product offer, say a special prebuild or 3x copies of a nice rare card for Xgran but only 500 or so of the product will exist, that would also make the auction house quite interesting. Of course you shouldn't allow someone to buy more than 1 of that product, i can see some people buying like 100+ 3x copies of a nice 5* and going straight to the auction house to make a profit.
Note: Everything I said is about shop is NOT guarented or even remotely close to what could happen, just some random thoughts