I had my right side fog light burn out 3 times so far this year. I decided to pull the casing out to take a good look for cracks and found water inside. I didn't see any obvious cracks but decided to remove the lense to remove the water inside. Should not have, because I ended up breaking the glass. I saw the post of some in here selling the lense replacement, but I was a cheap #ss and decided to DIY. I just ordered abrasion resistant, UV resistant polycarbonate (lexon) and cut out my own lense~ $10 for a 12" x 12" x .125" sheet.
I just used a dremel to cut out the lense I traced using the outer fog shield lense cover. I re-attached the lense with weathstriping adhesive and globbed on extra silicon for added water protection. It's drying right now and I will install it later this week. It took ~30 mins to cut and re-glue the lense back on.

 

this is a good write up as well: (scrol down a few threads)

http://www.acura-tl.com/forums/showt...ighlight=lexan