Very, VERY rarely Neiman Marcus has an end of season sort of clean out event. It's rare that any common sizes are left though, and sometimes none at all. Christian Louboutin has spoken out about fakes and made a statement that any site that isn't the official CL site that has "Louboutin" in the name is a fake.
Ebay is an option; however, fakes are prime there too. If you're buying a pair online, you can post up a link to the auction on ThePurseForum 's Louboutin threads, and the kind ladies there will be able to help you authenticate them. This has been helpful for me in the past. Hope this helps everyone!