This company's primary interest seems to be selling replacement parts for pre-existing M/S rifles. If you assembled a rifle, using the action, magazine and trigger group and then added a barrel, the cost would be unrealistic IMHO.

It would be much easier and less expensive to start with a little used original M/S and convert it to the caliber desired and possibly add a custom stock. The caliber would have to be compatible with the original one for it to function properly, of course.

I have seen worn out M/S 1903's in Africa, but never elsewhere. Most of the ones offered for sale these days appear to have been used very little.