Best addon to make money on the AH?

[Bollwerk]

Just wondering if there is any particular addon that works best for making money on the AH. i.e. Keeping a history of prices and letting you know if something is priced unusually low.

[Ualaa]

When I was doing the auction stuff...

It was a combination of using Auctionator to post items.
Basically make a bunch of categories, and add your items to each category.
Set a minimum price, a maximum price and a 1cp undercut amount... and list your item for whatever duration, depending on how frequently you will un-list and re-list (shorter duration the more active you are) the items...

And then on the buying end.
Auctioneer, still seems to be amongst the best.
Scan the AH, twice a day for a week or two.
The weekend and the weekdays, each seem to have their own variance on what is normal.
Once you have a set of scans, for the database, scanning again lets you know what is listed low both the bid amount and the buyout amount.
Not saying buy something because it is low, but to consider it; there's no guarantee anything sells at all, even if it is usually listed at 100g.

The combination of those two addons is probably close to the best auction house playing.
You could get by with just auctionator, if your market or niche were small enough and you were active enough in the market to know what gems, cloth, enchants, whatever... was actually worth.

[luxlunae]

Auctioneer has you do regular scans of the AH and then you can do a "resale scan" of those results to tell you if anything is low priced.

You're better off actually only doing that with items that you understand however, because people love to mess with this feature by listing worthless items for a lot of gold just to trick the addon. I'd recommend looking at the editorials on the undermine journal to start with ways to earn money.

[Iru]

My personal recommendation would be TradeSkillMaster & Auctionator

Go here and here for more info