[BrickPig]

Did you mean a windshield sunstrip, which is tinted vinyl and adheres to the top portion of the windshield, either on the inside or outside?

Or did you mean a visor, which is made of opaque material and mounted externally above the windshield?

 

[BrickPig]

I got mine from eBay by searching for "Scion xB 08 sun strip". My install at:

https://sites.google.com/site/brickpigs2011xb/home/5-windshield-sunstrip