This isn't a big deal really. Don't even try to say that you NEED it to make your icy prism, you don't. You just want it to make gold, which makes it an act of greed.
I know, the whole need/greed term is a bit off in wow, since you don't need anything for your char to survive. It's not as if it'll starve if you don't win a roll on that piece
of ham.
Personally, I greed regardless. I've got half a stack sitting in my bags for days when I bother taking the trip to the bank for gems to make a prism. My only reason to
need on it would be if someone who got on my nerves during the run presses need or tries to con by rolling last.