On Quel'danas you can buy Naaru Rations. (Naaru Ration - WoWWiki - Your guide to the World of Warcraft)
You can buy it for 2,25 silver but if you sell it you'll get 2,5g
Now make this Macro:
/script local function buy (n,q) for i=1,100 do if n==GetMerchantItemInfo(i) then BuyMerchantItem(i,q) end end end buy ("Naaru Ration",20);
Have fun