You need a D1S 4300k bulb. Usually sold as Osram, Philips or Sylvania. They are all virtually the same. I think the oem ones are made by Osram, but not a big deal.
4300 is the color of the light, pure white and matching the other bulb. Going higher makes the light bluish as you see on some cars.
You should be able to get the bulb for around $40. Just google or look on ebay. Get a new one that is DOT stamped. Otherwise they are Chinese replicas.
Audio: Jehnert Flatline speakers, Mobridge M1000 DA2 prepro, Helix P-DSP, Zapco Z-150.6 amp, iDock on dash
Performance: Protuned Cobb, AR Downpipes, ER FMIC/CP, DCI, RB turbos, KW V2 coilovers, AEM 320E LPFP/ported fuel rail