Exactly what I was doing! Half an hour got me just over 370K - but I'll admit it was just plain great fun! I can see myself doing that quite a bit before actually leaving the "safe-zone". Is there a suggested cash cap before doing so? Number of missions? Level?Try following the space police around at a nav beacon, wait until they've almost killed a pirate then land the last few shots and steal the kill. Easy money for the early game.
Be careful of the cops with friendly fire they'll turn on you if you hit them.