It's a sealed halogen assembly, but worth $45, I dunno.  So with a little adaptive engineering, we ought to be able to find and retrofit affordable lamps into the holes in the cap.  Which is what I'll likely do if I crack out another lens.  Who the heck ever really uses that pair of lights anyway, so why pay 90 - 100 bucks a set?
I'm not sure the $12 NAPA fog lamps are a power match to the ones we have, which are actually "driving" lamps for added visibility on the open highway;  you know, the ones you hate staring at on oncoming cars.  I think ours are like the 55 watt halogens at this website, where a pair of them can be had for less than $60 and free shipping:  http://www.autopartswarehouse.com/category/headlights_-and-_lighting/driving_-and-_fog_lights.html .   Click on "Driving Light".  Also check JCWhitney.com.  You'd have to make sure any replacement is a size match, of course, and had a useable bracket attached.