As I understand it is a Walther PPK clone, so
possibly Crimson Trace Lasergrips would work. At over $300 I would make sure first.
http://www.crimsontrace.com/01-1970
My opinion though, forget the laser gimmick, and learn to shoot well with the sights. I never want to trust my life to batteries, and circuits.
Lasers are great training aids, especially for dry fire practice to see If you are pulling off the target, but are of limited value for actual SD. JMHO.