problem with painting is its going to chip either way, powder coat or spray (water or cellulose). you will end up base colour around the teeth and once chipped corrosion will work its way under.
motocross Aluminium sprockets fair better as they are anodized which eats into the surface, especially hard anodized and can be purchased in multiple colours.
if you try paint,its got to be cleaned well and etched, maybe even anodized. Ive fitted chrome belt sprockets to Harleys and even the rubber/Kevlar compound peels after a time.
there are a few enamel paintersbut even the old bread bins chip after a while. a lot of coloured sprockets are on low mileage show bikes.
best I cann suggest is call into a spray shop like Bristol powder coating or Pharon these are more specialised industrial coaters rather than a bike sprayer
