@pindac Very nice. Is the sub-plinth beneath the main plinth, or is it a plinth within a plinth? Mine is 6 layers and sits on Townshend pods, but I might build a sub-plinth if I go for a second round.
One thing that decreased my cost importing the Panzerholz was having panels pre-cut and shipped in boxes as opposed to whole sheets that would have required a pallet. I will look into the others you mentioned as well.