Just like the Mass Effect wiki, there is a parallel for Dragon Age games called the Dragon Age wiki. It has been the best resource so far with information for almost everything in the game you would want to know about. Another good resource is GameBanshee’s Dragon Age: Origins subsite. It’s not quite as up to date as the wiki; single author guides can never keep up with a wiki, but it does have fewer ads and a better layout for some things.
I. List of Merchants
I frequently found myself in Dragon Age: Origins with quite a few sovereigns to spend but not sure what all the available merchants were, so I could visit them all. The wiki has a nice list of all the merchants in the game to help with this. It is especially nice for getting new crafting recipes as soon as you gain a new rank in the skill.
II. Merchants with Infinite Stock
Some merchants have infinite stock of certain crafting items. All this comes from the wiki. I just reorganized it a little bit. Some of the merchants become unavailable based on your actions or after a certain point in the game. I note this when applicable in parentheses. *Spoiler Warning: The notes are spoilers.*
Alimer in Dust Town, Orzammar
Bartender in Gnawed Noble Tavern, Denerim Market District
Flask (Figor in Orzammar Commons sells cheaper if available)
Ruck in Ortan Thaig, Deep Roads (unavailable if killed)
Quartermaster in Circle Tower
Varathorn in Dalish Camp (unavailable if you side with the werewolves)
III. Junk Items
There are several items you find in containers and the corpses of enemies that have no use in the game. They can be freely sold to merchants for a few silver pieces each. Unlike Dragon Age 2, the game does not give any indications that these items are junk. As I played the game, I looked up all the items I could not find a use for on the wiki noting down the ones that can be safely sold to vendors.
Note: There may be more items to this list. These items are just the ones I found in my playthrough. I will add more as I find them.
- Iron Ring
- Blank Vellum
- Engraved Silver Bowl
- Gold Ring
- Private Documents
- Fancy Vase
- Silk Carpet
- Silver Chalice
- Emerald Ring
- Silver Ring