Even if it is the work of a American smith, (I have not seen any "production" swords from China that look this good!) I would think that it's value has been lowered if the mei has been removed. I think it looks similar to some of Rick Barrett's katana and his typically bring $3,000 to $5,000. If it is from DiCristofano, well... his work is harder to find and higher priced. The photos of the other Nihonto also look very similar.
The patina on the nakago of very troubling. From the photos I must agree with those that say it is artificial. I cannot say that there was/is any attempt to deceive. I have seen people rust a nakago on a new blade to get the "proper look" just for their own pleasure.
Ether way, I believe that having removed the mei and aging the nakago has lowered the value of a fine katana.
Dave P