Daniel, the Osram Silverstars are available in the US. You can try www.suvlights.com,
Candlepower sells a rebadged Silverstar, you will have to email Daniel Stern at lighting.mbz.org since his webpage only lists cibie but he does carry the Osrams. I good buld test is at www.autoexpress.co.uk,
they rate the Osram Silverstars and the Philips Visionplus as number 1 and 2.