Just had my xenon headlight go out. How can I test that it is the bulb?

Seems they are quite expensive and reading we should replace both as the change color with age.

Want to make sure it is the bulb before I go plop down $300 and find it's not the bulb and can't return it.

Also, I see the photo on Pelican Parts shows what looks like a bulb and balast? Other sites show just the bulb.

thanks!

P.S. Any suggested place to get good bulbs low cost?

 

If you remove both headlights you can swap the bulbs side to side and see if the problem moves.