Hey, I leveled engineering to make my own ammo mostly because :
http://www.wowhead.com/?item=33803
1) it was 6 DPS higher than the other's available
2) i could mine veins whilst grinding and have materials to make enough arrows, 1 arrow box would make 1000 arrows and they can be stored in an engineering bag, so i would walk around with a 24 slot quiver full of arrows, and 3-6 boxes spare in my bag.
but now i have the rep with Violet Eye and i have available:
http://www.wowhead.com/?item=34581
but something that bothers me is the freedom offered having to buy the arrows from a vendor who's only in shattrah compared to carrying around tons of my own, which take up hardly any space
for example, doing raids it uses up a lot of arrows when we are making progress in SSC and TK, but when we wipe often and give good tries on bosses it consumes a lot of arrows.
do people ever run out of arrows doing raids? or do you carry extra stacks in your bags? if you could say how many you go through, and do you ever have to ask for a portal/hearth to get more arrows?
one last thing, i think blizzard sucks that we have to buy arrows from vendors and need some crap rep for higher ones, why can't we make our own like rogues make their poisons?