The best bet is the internet.
Joking aside You are probably not going to ever find some one selling whole sale bits on the cheap.
especially hot bits.
and at that for newer kits you are going to be hard pressed to find any bits at all outside of auctions till they can figure out what bits sell then everyone else prices it out.
Its possibly better and faster to buy the kit your self and sell the bits you dont want to get some or even more money back. (if you are willing to spend the time)