Amazingly there is a market industry for selling and purchasing celebrity photos. You have to be careful however that you are not purchasing a poster or something like that if you are looking to purchase authentic photos of your favorite celebrity.
On the other hand, some of the photos that are taken by paparazzi are sold only to tabloids and even then the price for celebrity photos is down a bit. According to sources it is down at least 3 % from what paparazzi will usually get paid by tabloids and magazines.
Sometimes you can sell celebrity photos through an auction or something of this nature and you can definitely purchase them by auctions. Many of these auctions are via the Internet though so as far as the photos being authentic that is a difficult decision. There are some individuals Kelly Stables who will claim the photos are authentic and they are actually copies of the original. You will never see the original but you will receive the copy with the claim that it is authentic.
Now if you are in Hollywood and you do see a celebrity and take the photo then you undoubtedly know its authentic. But actually getting photos is not as easy as it sounds. Some people just get lucky and will catch a celebrity somewhere. Most of the photos that are taken are of certain award shows and Hollywood benefits. Then, you will see celebrities posing for a camera. Otherwise you will see their photos via the Internet, in tabloids and magazines, and sometimes the newspapers. It just depends on the story behind the photo and why it is being printed or displayed.
Paparazzi are known for taking unexpected photos of celebrities and then selling them for a profit, they do not just take the photo for their own benefit. It is to make money by selling them. So, if you are looking for authenticity in a photo of a celebrity it is in your best interest to beware, it may not be original but in fact a copy. It is very difficult to purchase and sell photos of celebrities because it is so hard to determine the authenticity of the photo. Its probably not the best idea to purchase celebrity photos via the Internet or through an auction via the Internet unless you do not want to be curious as to whether it is the original or not. Paparazzi usually do not sell the celebrity photos to individuals. They usually sell them to magazines and tabloids. The best thing to do is attempt to get photos for yourself should you be in Hollywood touring the places where the celebrities go.