I think the base plate is 400mm SQ
It'll be ~150kg It was made not to flex and to hold huge mass. But I could roll it on an old skateboard!
Look I have no idea lets say $350.....The local welding shop made it up for me its well done heave and doesn't ring nor flex. You don't really need top plates to adj level as any EQ mount this is quite superfluous but I did get some sound alloy plates made
Cheers