Well I'm sure they can be on www.ebay.com just look for real life halo guns thats really it or else you can buy your son a lot of legos and spend a lot of money seriously witch one will you really spend on legos or ebay? =] GOOD LUCK
Well ive personally checked because they actually are pretty cool and Toy halo wepons don't exist, on the other hand you can get replicas of the halo3 crarbine,energy sword, or battle rifle for about 40$ each, but if your rich or something you can get several other replicaas for about 100-200$, its not easy but its possible, I'm not quiet sure what the size and quality is of the replicaas