Look at this AST-SK-1200 I am not sure if it is mechanical, but condition is nice https://www.ebay.co.uk/itm/AST-SK-1200-VINTAGE-PS-2-KEYBOARD-FCC-ID-GYUR15SK-READ-DESCRIPTION/183519392344?hash=item2aba9bb258:g:u2MAAOSwPGtb33DQ:rk:21:pf:0
Look at this AST-SK-1200 I am not sure if it is mechanical, but condition is nice https://www.ebay.co.uk/itm/AST-SK-1200-VINTAGE-PS-2-KEYBOARD-FCC-ID-GYUR15SK-READ-DESCRIPTION/183519392344?hash=item2aba9bb258:g:u2MAAOSwPGtb33DQ:rk:21:pf:0
As usual with these oldies that's relative. There are people that are willing to spend quite a bit on something like this. On the other hand you may get lucky and pick one up for cheap.
I looked on Ebay and Amazon and can't find any of this keyboards