Andrew, you might want to check out a DIY center, as well. Many stores still have NOS Mercury Vapor yard lights sitting on their shelves collecting dust. In fact, the Ace store that I work in still has a Cooper Lighting 175 watt Mercury Vapor Security Light sitting on the shelf. You might even find one in a dusty box, and be able to persuade the manager to sell it to you at a discount because it's "shopworn."