
Your best bet would be to contact the breed clubs. Are you in the UK? If so, these are your best starting points:
http://www.thenewfoundlandclub.co.uk/http://s117862056.websitehome.co.uk/This is the best way of finding a pup whose parents have passed all the relevant health tests for the breed (heart, hips, elbows & preferably cystinuria as well) and that has been ethically bred.
It is highly unlikely that a breeder will contact you in response to an ad like this. Reputable breeders generally don't need to go looking for buyers as they will have a long waiting list already (I've been on a waiting list for my next Newf puppy for almost a year; the litter isn't due until 2009!). In addition, brown tends to be less common which may mean you have to be very patient
Opportunity knocks...
Temptation kicks down the door