I charged $50.00 a valve cover for the ZZP ones.
Aluminum dog bones, they usually run about $25.00 to no more than $30.00 to polish. If you want aluminum parts chrome plated, I have to send them out of state to have that done. They don't come out nice to my standards if they are done here. But if they are steel, like the stock ones...

they can be chrome plated here no problem.
I also powder coat them a lot of the time too. Like the ones in the pictures I posted. Red, Blue, and purple too. (colors to choose from are in the 500's)
~F~