Have read that the flasher lamps tech is called dichroic interference coating. Allows for look to be chrome, but emites amber colored light.
BAUS15 is available in amber version Sylvania #7507, Philips #12496 on the web for under $4 each.
The Diochrioc (chromed) version is Sylvania 7507LDA
under $8 each.
Have read here that people are using LED, but lost the links.