Tasty Nuts/Pro Bolt.U.S. Distributor (and a pretty good guy to do business with)
Not as tough as the steel stockers, you need to take a bit of care when installing and removing them- a slightly rounded hex wrench is going to get you stripped bolts. They look cool, though, and they don't rust.
That said, when I wanted the bolts blacked out on my XX, I just painted them. Took very little time and lasted a couple years before it started looking ragged.