Fritz 15 is a complete program. You don't need to buy anything else. Chessbase is THE database software to have of course, but unless you're high ranking you don't need it. Fritz 15 also has a database, but it's just not as sophisticated. The confusion comes from the GUI part of Fritz also being used in other products, such as Chessbase. You will get a decent engine (that can easily be upgraded), the GUI and a database when you buy Fritz 15; so no, you don't need to buy anything else. Whether Fritz is the best software for you is of course a completely different question.
Some sell at retail, some at discount. Doubt it's a "scam".
I would like to buy Fritz 15 from amazon.com: http://www.amazon.com/ChessBase-9783866815056-Fritz-15-PC-DVD/dp/3866815050/ref=sr_1_2?s=software&ie=UTF8&qid=1456922918&sr=1-2&keywords=Fritz+15
My question is whether I have to buy some additional Chessbase Software or this is all I need to install Fritz 15 and get it running. I heard something few months ago along the lines... "Fritz 14 is just a GUI on top, you need Chessbase below it."
So do I have to buy some other chessbase interface software as well or Fritz 15 CD/DVD is complete in itself and doesnt require any additional software.
Also 1 more question, I see that ChessCentral is selling the same Fritz 15 for $5 less and also with free ebooks. So I am wondering how can they sell something for less price than the manufacturer and still add a ebook or two to it. Is it scam?
The link for the same is : http://www.amazon.com/Playing-Software-Program-ChessCentrals-Fundamentals/dp/B016KWYDR2/ref=sr_1_1?s=software&ie=UTF8&qid=1456922918&sr=1-1&keywords=Fritz+15