I doubt it would be 40-50 each. I have had things water jet cut before in volume and the prices do not get that low. At least where I live.
It is a fairly complicated piece to cut and the aluminum is a fairly thick plate. I think that it would be at least a 50.00 chunk of aluminum and the flange has to be cut for the intake runners, bolt holes, and the injectors at a different angle and the proper depth relief to get the injectors in the right spot and bolt down the fuel rail. Oh and a fuel rail if not using the stock one.
I am not saying you can not do it cheaper as I have but to do it right is expensive.