I watch Texas arrowheads on ebay all the time. More often than not, there is one company selling cast of arrowheads. I don't know if you're wanting one cast, or to just purchase? Here is a link to their current ebay listings.
Ive made some out of wax. pour a mold then use a knife for shaping, then when you get the shape of the point use a nickel for the flaking. id do it for you if you wanna send me the wax email me firstname.lastname@example.org