If you missed out on the auction of one letter domain names, you still have a chance to bid on two letter domains. They are being auctioned off by Sedo and some of them have already received high bids.
For example, il.com has a bid of $85,000 already, and fw.com and px.com are currently at $25,000. There are still some bargains though, such as w9.com at $410.
By the way, check out the write-up on one letter companies.