So, I've mentioned before about using The Undermine Journal for pricing. It's simple, but every time you want to price something you have to alt-tab.
This is where TSM comes in handy. It can give you the prices for both your server and realm straight to your item's tooltips.
This is what you need:
Now, one of the great things about this is that it can include data for items that haven't been seen on your realm before. That way you can price them better, instead of guessing from the items that are on the AH already. So much easier, right?
You can just use one of the WoWuction or AuctionDB plugins, but I find using both helps me cover more prices just in case.
The only downside is with pet auctions. You will have to manually check them, but some time in the future I plan on writing up a massive compendium of pets and their current going prices!