This is a video I made up explaining how to obtain Emblems of the Black Demon on the private server Eternal -  Wow http://eternal-wow.com/
First off you need two macros

splitting macro
/run local g,e=0;g={GetContainerItemInfo(0,1)} e={GetContainerItemInfo(0,2)} if string.find(g[7],"200000G") and e[2]==nil then SplitContainerItem(0,1,1) PickupContainerItem(0,2) end

Buying macro
/run local g=0;g={GetContainerItemInfo(0,2)} if string.find(g[7],"200000G") and g[2]==1 then UseContainerItem(0,2) for n=1,GetMerchantNumItems() do if GetMerchantItemInfo(n)=="Emblem of the Black Demon" then BuyMerchantItem(n,1) end end end

   Make sure to put them in TWO SEPARATE macro's
   Next step put all you gold bars in the FIRST (1) slot of you back pack, making sure the SECOND (2) slot is EMPTY. Simple click the split macro once, then the buy macro, and boom you bought an emblem easily.
   Why should i bother with the macro? Because if you don't macro then you have to split each one by hand and that gets tedious when you can simple push two buttons.