This involves the stacking/selling macro which has been posted, but just a note that i thought of and tried the other day.
on my server i play on (Deviant WoW), there is a bow at 1.00 speed, which means i empty out of arrows pretty quick, so i thought to try it, and you can stack arrows 20000 per stack! therefore save running out on big runs and boss fights ^^ here is the macro i have for blackflight arrows,
/script local function buy (n,q) for i=1,100 do if n==GetMerchantItemInfo(i) then BuyMerchantItem(i,q) end end end buy ("Blackflight Arrow",200);
Hope this helps my fellow hunters out there ^^
EDIT: Also tried this on three other servers, great for those that have low drop rate, all server i have been on, blackflights sell 1.60s per stack, and sell back 6s per stack, with this macro, you pay ~3g per stack and rake in 12g sell back ^^