You could have the frame powder coated any color that you wanted, but obviously that would have to be arranged ahead of time.
I think, for most people, that some shade of black is more the traditional color that we see frames in. Most factory frames are black. There's even a color named for it - Chassis Black.
There is also the optical illusion that black is "stronger." Your mind is trained to think of strong steel when your eyes see black. Your eye is trained to think lightweight alloy when you see silver. Black wheels look stong, silver wheels look light (same idea w/frame). That's a theory that I just made up by the way, no basis in provable fact.
Many powder coaters charge less money for black and run the black more often. The demand for black drives the price down. Locally, I can have black done in 2-3 days, but thru the same coater, any other color is a couple of weeks. And the colors cost me a little bit more money.
angela