In my mother's childhood, she said her brothers constantly found arrowheads along a riverbank. In my earlier years, I only found one arrow, a broken one, and I believe I had one authentic one given to me.
Now, when you go to the tourists sites, you can buy arrow tips for $1. I don't know if they are machine made but my guess is that they're created with modern materials.
Now, if I ever find my arrow lying around, I won't know if it's authentic or was one of the ones I bought for $1.
The photos above are from Woolaroc, a museum near Bartlesville, in the Northeastern area of Oklahoma.