I was once given a mini of Champagne (ie pre Yvresse name). It's an intense creamy bubbly floral. I must be hypersensitive to some note because there's something that disturbs me, like a aldehyde multiplied ten times that becomes as thick as cream. Almost as if I couldn't breath, so thick it is. It's a note I remember noticing in the past (when I was not into perfumes), but not in recent perfumes. (I briefly sprayed Yvresse in the new ugly bottle in a store, didn't get that impression, but I was under nose fatigue so I cannot say how different it is). Therefore, I am not the best person to judge it.
I have not been following prices on ebay or the like. Such prices would not be uncommon for 100ml of vintage perfumes from big houses, but I don't think Champagne is particularly collectible, so I'd venture saying that the price is a little bit on the expensive side. But as said this is an uninformed guess.