Regarding the older SLR's, especially Nikon...

[railman44]

Is there really any difference internally between a chrome or black body same model camera? I somewhat remember the black body cameras being a little more expensive but maybe that was just for looks?? I would be very surprised if there really is a difference between the same model. I don't think way back when you could even buy a Nikkormat in a black body...

 

[ksmattfish]

In most cases it is purely fashion.

 

[Rob]

I was told that it costs a bit more to get the special plastic coating to apply, therefore black all over is dearer than the silvery coloured alloy at the top. The black does look slightly nicer when mint, but actually wear is more noticable in heavy use as it tends to scratch off where the shoulder strap triangles meet the body.

As Matt quite rightly says, it's a looks thing.

 

[Hertz van Rental]

They brought out the black bodies to appeal to pros - or wannabees. All that chrome used to reflect studio lights and you could often see the camera reflected in things. Some pros used to put black electrical tape over the shiny bits. Companies like Nikon picked up on this and started producing black pro versions - naturally more expensive, even though it was far more expensive to chrome-plate the metal bits.