What I have heard and seen of the available DLC hasn't really intrigued me. I've redeemed my codes, but have yet to use one of the items. Have been to Sulchers pass on my way from the Circle tower to Redcliffe, but have yet to follow up on that.
To be worthwhile for me, DLC should add something new and unique to the game, but also fit into the existing world: Expand on lore that is only touched briefly yet, show new aspects of familiar places and characters, etc. In that regard, I guess Shale fares better than Wardens Keep, which seems to open up more loose ends than it closes.
Something I might consider buying would be a questline resolving around some character or faction that would eventually open up a new specialization/skill tree. Should provide a good mix of dialogue, exploring, puzzles and fighting and as a reward something that opens up new tactics to use in the vanilla game. I haven't played enough of the game yet, so no idea where it could tie in exactly.
In general, the more fleshed out it is, the more story it has to offer, the more likely I'll become a customer.
What doesn't really interest me are mere items, houses or Chantry-board type "fetch this item" or "clear that dungeon" quests that do not shed any light on history, geography or important characters.
As for the pricing: considering that engine, toolset and part of the assets of the vanilla game can be reused, cost of DLC should be more reasonable than the current offerings. A lower price could actually lead to more sales and thus generate a larger revenue in total.