Lord no, not in todays gun market. You will pay a few dollars more for a LH gun (rifle or shotgun). But today, all the major manufacturers make Leftys. Weatherby, Browning, Ruger, Savage, Remington, Winchester, etc.
If your son has a dominant left eye, don't force him to shoot right handed.
I'm just a little sorry that Rem. hasn't made the model 7 in a LH. But I'm tickeled pink with my Browning Micro hunter LH in 7-08 which by the way would be a great caliber for a young shooter as would the .243 or 260 Rem.