Campus111 via eBay offers the HID 4300K Xenon Headlight Conversion Kit
with free shipping
. That's the lowest total price we could find for any size of this bulb in this color by $12, although we saw it for $3 less last week. It's available in sizes H1, H3, H4, H7, H8/H9/H11, 9004/9007, 9005/HB3/H10, 9006, 880/881, and H13.
Of note, it's also available in 6000K, 8000K, or 10000K for $1 more.