It looks fine to me.
They would have been made sometime between '68 and '71, probably closer to '71 than '68, as he would have had to gain some experience with handling hot glass before embarking on something so large and complicated.
I have been trying to keep count of them as they have appeared over the years, I think yours is possibly the 37th I've heard of, but there is a possibility I have counted the same one more than once, as they changed hands and there might be some I've missed.
There may be loads sitting in folks' houses and they just like them and keep them.
Something is worth what somebody is willing to pay for it, in that place at that time. I think this came from that well-known auction site recently? Your winning bid was what it was worth. Somebody else was not willing to pay
quite as much as you were, but not a lot less.