In general there are three sources of puppies for every pure dog breed, each coming with pros and cons, and golden retrievers are no exception:
1. Puppy mills: this kind of dog breeding is based strictly on profit. This means they try to create as much money with sales as possible. Dogs are often bred in shortage of space, hygiene standards are low, dogs don't get individual treatment and all this leads to very high possibility of health and behavioral risk.
Puppies of golden retrievers from such facility in most cases end in pet shops and are relatively inexpensive. You can get one for few hundred dollars, but you got no guarantee the dog will have no health problems, which in the case of goldens are mostly joints, eyes and heart. Getting an inexpensive pup could end as very expensive life experience - for you and your doggie.
2. Backyard breeders: most of them are driven more on enthusiasm than profit, but getting a dog from a backyard breeder carries almost the same risks as ones coming with puppies from a puppy farm. Typical backyard breeder can very hardly afford paying for all basic clearances for the dog and it is even more unlikely the same was done for pup's father and mother. Such dogs are also more likely prone to behavioral problems.
In the end of the day, you may get a cute golden retriever puppy for few hundreds, sometimes even cheaper than from pet shop store, but the probability of getting a healthy individual is very low, very likely less than 20 percents.