Where can you buy a 357 Model 60 Lady Smith?

That depends entirely on your state and local laws. If you live in New York City or Washington D.C., the answer is "you can't legally purchase a handgun".

If you live in a locality where it is legal, check the phone book for sporting goods stores or gun shops and go shopping. If the local shops don't have what you want, go to auctionarms.com or gunbroker.com and a purchase can be arranged through a federal firearms licensed dealer near you.

Note: the Lady Smith model 60 in .357 is rather stout when firing full power loads. Practicing with .38 Specials is considered wise.