Back in 2007 when I did it, it was magic longs strung and we only lost like 38gp an alch.
Looks like it's maples currently, I mean it has to be something you can buy 150k of.
So it'll prob cost you around 15m I'd imagine for 99 magic. That's worth it.
I would post on magic long and say buying 150k at 1300 each, you might find sellers at that price.