I think he means the chrome at the bottom of the window. The lower trims have a black trim piece
Online Mazda dealers can give you about 20% discount from MSRP.
That is about the best price you can get.
Local ones, probably between 10-15% off + TAX.
If you go to Japan online store, you can chrome all the way:
http://item.rakuten.co.jp/samuraiproduce/axela-fog-type1/
To buy OE:
mazdaparts.org (for accessories) for parts, you need to contact them.
Same for
waynemazda.com
Recently I tried this one:
http://www.partswebsite.com/mazdawholesaleparts/
All of the above are MAZDA dealers.
First, you need to find the part #.