chroming or in this case black chroming is plating of the parts, when you chrome something the part is dipped into different solutions to "plate coat" the parts, i heard that black chrome is even more involved than regular chroming.
all my babbeling said, if it is in fact "Black Chrome" then $100 a wheel i think would be a decent price.
powder coating will look like paint
black chrome will have a chrome look to it, it is hard to explain, but when you see it you will know what i mean, just tell them to show you the difference
chrome
http://www.truckstuffusa.com/ec2chro...sbydeezee.html
Black chrome
http://www.truckstuffusa.com/stainsteello4.html