First and foremost...you mention being unintelligent in your post, yet you can't even spell correctly.
Next, the fact that you say a spayed or neutered dog is only worth $50 tells everyone on here that you are more than likely a breeder or that you base your OPINION on the dog being able to breed.
If the dog has been fixed then the person obviously has money invested into the dog. Veterinarians will not spay or neuter unless the dog has current vaccinations. Depending on where the dog was spay or neutered at, the price ranges are roughly from $100.00 to $350.00. In addition to that fee, they also have to pay office visit fee and other surgical fees. Taking one dog in for this procedure can run $500 by the time all the fees are added up. Sometimes people will ask a rehoming fee to cover what they have in medical expenses of that animal.
Maybe next time try using your head instead of your.