Mainly this addon was written to keep track of my Corpse Dust and give me a LDB-feed on how many I had left, I have now redone it so that it can be set up to buy other items as well. So far it has worked great for my hunter's arrows and my paladin's "Symbol of Kings". The icon and tooltip on the LDB-plugin updates itself according to what item is set to be bought, by default this is set to buy 20x Corpse Dust.
A simple addon to fill up your bags with a set amount of one type of item when ever you visit a merchant that sells them, also includes a LDB-plugin to show how many of that item you currently have in your bags.
Optionally you can drop the buying part and just use it to track any item, like Soul Shards for a Warlock.
If you are looking for a more advanced reagent buyer please look at FreeRefills.
/bcdust for this menu
/bcdust number X - number to set amount of items to buy
/bcdust item [Corpse Dust] - Shift-click on the item to insert what to buy
/bcdust minimum X - number to set lowest amount of items before changing LDB icon
/bcdust track Reagents - set what tracking to set when you right click the LDB
/bcdust reset - Resets the configuration to default settings