What is a bottle of bundaberg black vat 100 1985 worth?

That is an Excellent question!

I am aware that a work based auction sold a similar bottle for $2000.00 - July 2009.

I have also seen the item for $600 commencing price on ebay, and I have seen it sold on an alternative auction site for $250.50, so the worth of the item is very much in the buyer's wilingness to pay.

Sorry, not overly helpful, but an answer none the less.

Regards

Peter