I know a place where there are many high-grade toys called "Next Age". I think you can find what you want.

There are one or two toy model shops at the east 100 meters (Ginza Cyber Plaza) of the intersection of Jiefang Road, Shanda Road, which is the west side of the auditorium of Dong Jiao Hotel (next to the savings office in the middle section of Jiefang Road of ICBC). The landlord might as well ask, they will definitely solve the problem.

I wish your son success in his studies!