My old lights had H4 HID bulbs in them, from eBay for around $50 including shipping. I had to buy a set of new H1 bulbs to suit these, for around $9 on eBay, including shipping. I kept the original ballast from the original eBay kit, and just changed the bulbs over.
You can get a whole H1 kit for around $40. Here
35W XENON HID Conversion Slim Kit H1 H3 H7 H8 H9 H10 880 881 9005 9006 All Color | eBay