Green laser pointer is available in Ap Liu Street. The cheap ones costs slightly over HK$100. A good one with ~15 mW power and using 123-type lithium battery cost about $250.
I recommend the one that uses Lithium battery because green laser isin fact a 2-stage system (unlike the red one which is just a simple laser diode,andconsumes little power) that consumes much larger power than the red ones.