These can be made and antiqued so easily that it is very hard to count on getting original points. A good reproduction is worth this much, but if you have your heart set on ancient points there is no guarantee you will be getting what you want. This is especially true for the Paleo Points like Clovis, Scottsbluff, etc. After being in this business for over 14 years I never saw anyone that could really tell you which stone point was real and which one was fake every time. There are hundreds of people who will tell you that they can tell, however.
Some dealers are better than others, but nobody can really make a reliable guarantee.
Nearly every dealer knows that only a small percentage of points ever come back, and even if they make this guarantee and get some back, they will make money anyway on the ones that aren't returned. This doesn't mean that dealers are bad folks. It's just a bad situation. The processes people use are so close to natural processes that a combination of techniques can produce many variations of surface wear and deposition. If you are buying some keepsakes for your grandkids, use the lower grade and price range points to help ensure they are getting something old.