Sunil I can see the wheels turning but before any one buys craws from a different local and stocks them think about the results ,if any, to your pond. If they are like fish , which I suspect , will they live and thrive in you local and what effect will they have on your pond. I don't know the answer but would want it before I act. Will, for example , LA craws kill off you native ones and then die out because they can't take the cold winter ? Those type questions come to mind.

crawfish link --
http://aquanic.org/beginer/crawfish/crawfish.htm

I saw an article recently about a "Rusty Red Crawfish" that , if I recall , was a problem up north. I can't find the article and am hazy on it anyway.