Yeah, I may have to re-think my thoughts in my original post. It does seem the old Thunder's are creeping up a little more.
Here's an original Thunder II, only thing is it's in Japan, going for a tad over $1,800 (£1,300) - plus shipping. 😏🤔 (Seems another dealer has the same bass -- or at least it's the same picture -- at a slightly lower price)
https://www.ebay.co.uk/itm/254810812956