They're officially called "side turn signals/ side flasher unit".
Here's the schematic of them, in drawing "C", as well as the part numbers:
Type in Year, Model and then select "Key Word Search", then enter in the search box at the bottom of page: SIDE FLASHER UNIT. Once it comes up, click on the camera icon on the right side to see the schematics.
http://www.myisuzuparts.com/

Here's another source of OEM parts: This one gives you prices right away, the one above does not, but it has better diagrams.
http://www.Isuzuparts.com/partscat.html

I would think you could try ordering the entire unit thru Merlin or maybe some junk / salvage yards in the U.S.

The OEM lenses is amber, but several have bought bought clear or white.
This brand makes really high quality LENSES (not the light/ unit itself). http://www.klearz.com/products.html#isuzu_vx