I found two sites when looking to replace my white fog light bulbs with yellow.
www.hellausa.com is one, the other is Susquehanna Motor Sports Ph; 610-944-3233 or their email is;
orders.mosports@verizon.net. Both sites had replacement headlight bulbs, just remember to be careful and pick the correct one for your vehicle. You can give year and vehicle model and type, they will be happy to assist you. Just remember these HID Bulbs are NOT Cheap! Good Luck, Robert