You could paint them with Sophisticated Finishes Blackened Bronze. It's the closest match to ORB I've found. The paint actually contains fleck of real metal, so it looks quite good. Since they're not actually side by side, it would likely work. I bought it at Rejuvenation, but have since also seen it at craft stores like Michael's and Joanna.

I used the paint on a mailbox slot that's just pot metal that I couldn't replace when I redid my door hardware to ORB. The slot gets 6 day a week wear, and has held up well for 3 years.

Another thought would be to invest in new knobs for the inside crystal, but that's likely more expensive than you were thinking.

I was looking to change the color of my chrome fixtures and someone suggested this site.

Here is a link that might be useful: Shor International