Margiela. Brass with matte grey color (it looks to be a worn/textured finish in the pics... it's not... it is a flat grey)
Geller. Brass with blackened gold finish
Are we talking affordable stuff, as in really cheap? There's an H&M on Newbury St, and a few blocks away at Copley there's a Zara and Club Monaco. If you're looking to go upscale, there's also a Barneys in Copley which is probably the best, but there's also a Saks and a couple others.