[Taragot]

Perhaps his grandfather does not want to buy used because it feels somehow inferior to him or he does not trust internet things like ebay? That would be typical for his generation where you would have gone to a real music store and buy the best instrument from their sortiment you could afford without all the other options in mind offered today. It's true that a Chateau does not have that brand magic ("My grandfather gave me a CHATEAU alto!) - but it should be a super solid instrument and a good option if buying in a music store is prefered.

 

[Taragot]

The Chateau CAS-80GL is from their Vietnam-built line and the same as the VCH-800 (V for Vietnam). I think that these are the same as Thomann Handmade, which cost al lot less (1000 Dollar) and can be had with all kind of finishes:
https://www.thomann.de/de/thomann_mk_ii_handmade_alto_sax.htm

I did not play one for myself but heared good things about them

If the thomann return policy is the same as in Germany, it could be easily returned.
Perhaps something to consider....

 

[Taragot]

I think that the kessler handmade and the chateau 80 and the thomann handmade are basically the same horn made by tenon in Vietnam, though the case, mpc etc may differ. But I do not know for shure.