Any good paint supplies but be aware that its a pretty futile exercise as you'll need exceptional vision to even notice the difference between the shades plus you'll be paying a few quid out to get 10 shades of colour made up just to spray onto cards and not really endearing yourself to a bodyshop to mix up ten different mixes and lacquer them just for you to decide.
Take a wing mirror off and go to the paintshop itself to decide looking at the colour charts mate.