Opening day tickets at the new Yankee stadium are already listed on eBay. There are over 70 listings for the most sought after game of the upcoming 2009 MLB season. If you're interested in attending now might be the best time to bid as demand may be a bit lower now. As we move into the spring demand will only increase as the new stadium is hyped more and more and the weather gets warmer.
Right now there are a couple pairs listed for Buy It Now's for $399, which isn't bad for NY ticket prices. Here is a link to check out the auctions currently listed on eBay: NY Yankees Opening Day Tickets.