If they are made by a professional knife maker, the majority of the cost will be labor, I imagine. If they are made of high grade steel, I think that $10 each would be appropriate. If they are sharpened to razor sharp edge, matched to eachother exactly in weight, and weigh no more than 250 grains, then $15 each would be appropriate. This is assuming you will be using the points for hunting and competing in price with factory-made broadheads.
If they are made to the exact specifications as the originals and can be considered collectors items, the price would be much greater (x3 or more).
If they are being made for display and the steel is not high grade, then $5 each seems reasonable.
Just my opinion. The prices may seem a bit low because there are a lot of arrowheads available on the market.