Have you tried rockauto?? The dealer wanted like almost $200 for a foglight on my GMC, rockauto was under $30.
Got my replacement unit in from Rock Auto thanks to Fobroader's recommendation. Was $134 including tax, shipping and exchange (and a bulb) as compare to the dealers $228 with tax.
Took me about 1 hr to install: 2 screws and 3 fasteners. Good news is the replacement is plastic, not glass, so should be much more robust
When (not if) the other one goes I will do the same.
No noticeable improvement to the light output, may try some different bulbs and see if that will make a difference.