Hello,
$600 is VERY LOW PRICE for a healthy dog. I would recommend visiting the following link
American Brittany Club They can help you find a breeder. You can also search on gundogbreeders.com and gundogsonline.com
Make sure BOTH parents of the puppy you buy are at least 2 years old and that you get PROOF (and are given/shown copies of) their health clearances showing clear hips, elbows,eyes, etc. No health clearances NO puppy! You don't want to take the chance that the breeder is breeding dogs with bad hips.
Hope this helps you out, I am happy to try and answer any questions for you.