Cyndayco,
Please, I am asking you politely, stop doing ebay searches for Tahitian pearls. What you are finding are mostly Chinese sellers listing Chinese cultured freshwater pearls as Tahitian and South Sea just like the example you gave. They are dyed. It's fraud and it is all over ebay. Some sellers don't even take photos, they use stock photos they get from somewhere, often others' websites, and you would not receive the item in the photo. You will stay confused about what you are seeing and hope you can get a bargain Tahitian pearl strand for $100.
That said, there are a few trustworthy sellers of pearls and sometimes other gems some who are members here, some are not, but their descriptions are accurate and they know pearls. Here are some~I'm sure others will mention a few more. (This is not an endorsement or comment on their prices.)
Agustus-Collection
Ehret Design Gallery
RainbowIslandPearls
Pearl Society Online
There are also a number of online sellers of Tahitian Pearls and other types of pearls, where your money will buy better quality, and you will have many more choices than at a retail store. You'll see photos of the actual pearls and be able to get an idea what the baseline prices are for baroque, ringed Tahitians or round peacock Tahitians. Here are some to check out; this is not a complete list by any means.
Pearl Paradise.com
The Pearl Outlet.com
Kamoka Pearls.com
Kojima Pearl.com
Pearlescence.co.uk
Tahitian Pearls.biz
You can research these stores and get an idea of what the price range of Tahitians are, and especially the size, color and quality you like. I hope there is a necklace of beautiful genuine Tahitian pearls in your future!