Welll craigslist is not the *best* place for that, however, if you know what you are doing and you're able to examine the camera before you purchase it, that would help make things safe.
KEH.com is a standard bearer of used DSLR pricing, they have the Nikon D60 (body only), when in "like new" condition, marked at $350. In "Excellent" condition, marked at $330. Assuming the craigslist nikon is somewhere around "excellent" to "like new" condition, thats a pretty good deal. If it has a lens (probably kit) an even better deal.
You should be able to find a Canon 30D for a similar price, or the 20D for even less. Those should provide a more useful interface, and a more rugged, durable body. Olympus has some used bodies available at very inexpensive prices as well, like the E510. I think those would be better used options.