Philips D2S off eBay perhaps?
About three years back, I bought a pair of used 4300K colour Philips D2S bulbs off eBay. They were removed from a BMW as the seller wanted his headlights to display a blue colour for show purposes rather than the stock 4300K white colour.
Shortly after I received the two used bulbs for my stock, I had to install one of them.
One of the existing Philips D2S bulbs literally blew up inside the reflector at about year five of use. Upon removal of the headlamp assembly, I had to shake the glass bits out prior to installing the replacement Xenon HID.
The original bulb on the other side is still OK as is my used replacement. Both lamps are in constant use daily as we have full time Daytime Running Lights here in Canada and dipped low beam is the DRL. In other words, Sylvania, I do not know about, but the Philips seems OK.
The link below is to a file I have on the Philips D2S bulb.
http://www.**************/gallery/displayimage.php?album=3801&pos=1
Replace the **** with
disco3 co uk and insert a
period in each of the two spaces.