Always see both parents in person and see if you like them. If you like them then that is what ur pup will grow upto be. You can see and research about labs on the net and search for lab clubs around the world and study the breed standard to get an idea of the dog also see what is the breed requirement and if you can fulfill it. That is if the breed requirements fits ur lifestyle.
Always see both parents kci papers and also take them pup with the puppy papers. Most breeders wud say that they will give it later, but that does not happen in most cases.
Prices vary from 8k to 35 k based on the quality of the dog. It is always advisable to buy from reputable breeder only, although deciding who is good and who is not is always a gamble.