If I wanted to paint my case should I get the white for better color stick or would black be fine to paint over later as well?
You should be putting on a white primer (you can use a different color primer if you want, like black or gray, but it will alter the color of the top coat significantly) before you paint whatever color you want to put on as the top coat. So it should not matter which color you decide to get. You might also want to sand the keyboard before priming in order to improve adhesion, but we are talking about a keyboard here... it's not like it's going to see the abuse a car or gun would see, so i don't think it really matters.
You can cerakote it yourself fairly easily, except for having to sandblast it down to the bare metal, and that's not actually difficult or anything, it just requires the purchase of a decent air compressor, which is a couple hundo.
The single best tip i can give you: Get some plastic spoons, and practice whatever paint job you want on some of them. That way, you can test multiple colors, in multiple shades, and multiple top coats (flat, semi, gloss) to figure out the PERFECT color/paint job for you.