I've posted about this before...
A few Christmas' ago, the Ipod nano was selling like crazy on Ebay because they were in short supply. Going for about $500-600 a pop.
Very few people realized that you could buy them (and get them in time for Christmas) directly from Apple.com for retail price. So I listed quite a few auctions and had Apple "dropship" the Ipods for me.
Worked like a charm.