For spray paint, I like Krylon. It is self priming, sticks to plastic, a good range of colours, and is readily available. They sell it at Home Hardware, Canadian Tire, etc.
You can get spray cans of automotive paints at Canadian Tire, Lordco, etc. Thousands of colours, some places will even load the spray cans, which will give you an almost unlimited range of colours.
Hobby stores still sell small bottles of paint, Humbrol, Tamiya, Testors, etc.